UC-NRLF 


*B    553    E1D 


LIBRARY^     , 

OF  THE 

University  of  California. 


GIFT  OF 


Class 


LIBRAEY 

Pacifist  f^henbgtcal  j|ett(iwtti 

Presented,    by 

— — ^ 


CONVERSATION: 

ITS  FAULTS  AND  ITS  GEACES; 

OE, 

THE  BEST   MANNER    OF 

SPEAKING,   TOTING,   AND  PRONOUNCING   THE   ENGLISH   LANGUAGE 
CORRECTLY. 

COMPILED    BY 

Rev.  ANDREW    P.  PEABODY,  D.  D. 

NEW    EDITION:     REVISED,    WITH   ADDITIONS. 

16mo,  cloth  stamped,  marbled  edge,  pp.  150.    50  cts. 

PUBLISHED    BY 
JAMES    MUNROE    &    CO.,    BOSTON    AND    CAMBRIDGE. 

OPINIONS  OF  THE  PRESS 

ON    THE    PREVIOUS    EDITION    OP    THIS    "WORK. 

"  This  is  an  exceedingly  interesting  little  volume,  and  one  which  deserves 
to  be  carefully  read  and  studied.  It  is  not  only  a  very  interesting  publica- 
tion, but  a  very  timely  one.  There  is  a  tendency,  even  with  people  who  know 
better,  to  use  phrases  which  are  far  from  correct,  at  first  by  way  of  fun,  but 
gradually  they  come  to  be  incorporated  into  general  use.  Dr.  Peabody's  Ad 
dress  is  very  beautiftd  and  sensible,  and  treats  of  the  principle  and  sentiment 
of  conversation  from  a  high  point  of  view.  It  is  a  very  valuable  compilation, 
and  should  have  a  wide  circulation."  —  Boston  Daily  Advertiser. 

"This  little  volume  is  dedicated  to  American  teachers,  but  it  has  words  of 
wisdom  worthy  the  attention  of  all  classes  in  the  community."  —  Boston  Even' 
ing  Transcript. 

(1) 


CONVERSATION :    ITS  FAULTS  AND  ITS   GRACES. 

f  "  We  welcome  this  volume  as  a  timely  and  valuable  auxiliary  in  the  cause 
of  polite  learning  —  a  branch  of  the  education  of  the  present  day  which  does 
not  receive  sufficient  attention  from  our  authors  and  teachers  of  grammar  and 
rhetoric.  It  is  not,  however,  a  book  for  teachers  alone,  but  one  that  is  hap- 
pily adapted  to  general  use.  It  should  be  read  and  consulted  by  all  persons 
who  desire  to  speak  the  English  language  with  that  elegance  which  adorns 
the  conversation  of  ladies  and  gentlemen  of  genuine  cultivation,  of  taste,  and 
true  refinement  of  mind."  —  Christian  Examiner. 

"In  this  work,  which  is  dedicated  to  American  teachers,  the  editor  very 
judiciously  combines  the  principles  •  which  should  govern  conversation  among 
persons  of  true  refinement,'  and  points  out  the  besetting  vulgarisms  of  ordi- 
nary colloquial  intercourse.  Many  of  his  suggestions  will  be  found  useful  and 
interesting  to  those  who  believe  it  essential  to  every  man  and  woman,  with 
any  pretensions  to  intelligence  and  cultivation,  to  speak  the  English  language 
with  grace  and  propriety."  —  Cincinnati  Columbian. 

"  The  greatest  faults  in  our  conversational  habits  do  indeed  require  a  moro 
deep  and  vital  cure  than  is  to  be  found  in  simple  external  omissions  or  im- 
provements ;  and  these  are  admirably  treated  by  the  compiler  in  the  address 
delivered  by  him  before  the  Newburyport  Female  High  School,  which  intro- 
duces this  little  volume.  We  cannot  too  earnestly  commend  this  Address  to 
the  consideration  of  readers  of  all  ages.  The  compilation  is  most  judicious- 
ly made,  and  should  be  widely  circulated.  We  welcome  this  little  volume  as 
indicating  the  gravest  dangers  which  threaten  sometimes  to  make  conversa- 
tion more  of  a  hinderance  than  a  help,  and  also  as  one  which  in  a  lively  man- 
ner will  suggest  to  young  people  the  absurd  errors  into  which  so  many  un» 
consciously  fall."  —  Salem  Gazette. 

"A  pure  and  graceful  style  of  conversation  cannot  be  learned  from  books; 
but  much  may  be  done  in  the  way  of  suggestion,  which  is  well  done  in  this 
volume.    It  deserves  to  be  studied."  —  Watchman  and  Reflector. 

"  Conversation  :  Its  Faults  and  its  Graces.  —  A  little  volume,  but  in- 
structive and  highly  valuable."  —  Christian  Register. 

(2) 


CONVERSATION:    ITS  FATTLTS  AND   ITS  GRACES. 

"  The  design  and  execution  of  this  work  are  alike  felicitous.  It  is  intended 
to  secure  the  legitimate  end  of  conversation,  by  correcting  what  is  amiss,  and 
elevating  its  general  tone  and  character.  It  consists  of  several  lectures  and 
brief  treatises,  partly  American  and  partly  English,  which,  taken  together, 
form  as  good  a  manual  on  the  subject  as  could  be  desired."  —  Puritan 
Recorder. 

"  One  of  the  most  useful  books  the  season  has  produced.  It  should  be  in 
every  family."  —  Boston  Mercantile  Advertiser. 

"This  is  a  very  useful  little  work,  pointing  out  the  true  ends  of  conversa- 
tion, and  exposing  a  number  of  current  improprieties  in  writing  and  speatfr 
ing."  —  Methodist  Quarterly  Review. 

"  This  neat  little  work  is  made  up  of  a  lecture  by  Rev.  A.  P.  Peabody,  and 
several  English  essays.  Its  aim  is  not  only  to  direct  us  in  conversation,  so  as 
to  make  it  entertaining  and  morally  pure,  but  also  to  furnish  rules  against 
the  most  common  verbal  faults.  It  carries  out  its  purpose  admirably."  — 
Portland  Advertiser. 

■  It  is  a  work  of  great  use,  and  should  be  in  every  family.  The  hints  here 
given  would  tend  more  to  purity  of  language  than  a  year's  study  otherwise 
devoted."  —  Portsmouth  Journal. 

"This  little  manual  contains  quite  a  number  of  useful  hints  well  worthy 
of  attention."  —  Boston  Evening  Gazette. 

"  There  are  but  few  persons,  either  learned  or  otherwise,  who  cannot  taA 
this  excellent  little  work  with  profit.  We  most  cordially  commend  it  tt  ctw 
attention  of  all  classes  of  readers." — The  Sunday  News,  Boston. 

"  The  compiler  has  brought  together,  within  the  small  compass  01  om> 
hundred  and  forty-seven  pages,  principles,  rules,  and  hints  on  the  subject  of 
conversation,  which  will  prove  of  more  value  to  the  young,  (and  old,  too,  for 
no  one  is  too  old  to  learn,)  of  both  sexes,  who  desire,  as  all  should,  to  speak 
correct  and  elegant  English,  than  three  months'  tuition  in  a  gianimar  school." 
—  Yankee  Blade. 


CONVERSATION:   ITS  FAULTS  AND  ITS  GKACES. 

"  Conversation.  —  We  would  say  to  every  one  who  does  not  wish  to  come 
Into  judgment  for  idle  word?,  Buy,  read,  and  digest  this  treatise.  It  is  dedi- 
cated to  American  teachers;  and  to  teachers  and  their  pupils,  and  to  all 
America,  let  it  go,  and  fulfil  its  useful  mission."  —  The  Independent  Highway. 

u  Old  and  young,  educated  and  uneducated,  may  consult  this  small  work 
with  advantage."  —  Gazette. 

"We  welcome  with  pleasure  this  little  hook,  which  has  long  been  needed. 
At  the  present  dajr,  even  in  refined  society,  language  is  wofully  abused.  Young 
ladies  are  guilty  of  most  extravagant  expressions ;  young  gentlemen,  also, 
often  make  use  of  slang  terms,  and  the  rules  of  syntax  are  daily  set  at 
defiance.  This  book  is  called  forth  by  these  existing  evils,  and  should 
be  widely  circulated  and  read.  Few  can  study  it  without  improvement, 
none  without  pleasure."  — New  Hampshire  Patriot. 

'•  It  is  worth  twice  its  price ;  and  while  the  conversational  errors  to  which. 
It  adverts  are  of  such  constant  occurrence,  no  one  should  be  without  it." — 
True  Flag,  Boston. 

"There  is  nothing  so  indispensable  to  true  refinement  as  a  polished  and 
correct  manner  of  conversation,  and  there  are  few  things,  it  seems  to  us,  which 
Yankees  are  so  prone  to  neglect.  We  talk  rapidly,  and  care  so  much  more 
about  what  we  say  than  how  we  say  it,  that  conversation  often  becomes  en- 
tirely neglected,  when  it  should  receive  particular  attention.  No  man  con- 
verses too  well,  and  no  one  is  above  being  benefited  by  this  little  volume, 
which  we  have  perused  with  more  than  ordinary  pleasure,  and  which  we 
Strongly  ecommend  to  our  readers.  It  has  successfully  aimed  to  bring  to- 
gether -,:ic  principles  which  should  govern  conversation  among  persons  of 
trne  <-«r*  ement  of  mind  and  character,  and  to  point  out  some  of  the  most 
oommoi  and  easily  besetting  vulgarisms  occurring  in  the  colloquial  English 
ot  our  country  and  day.  It  is  a  book  which  should  find  its  way  into  every 
household,  and  which  the  young  should  carefully  consult."  —  Old  Colony 
Memorial. 

"  Such  books  as  this  are  greatly  needed,  and,  we  are  glad  to  see,  are  receiv- 
ing the  public  attention.  It  is  a  very  useful  book,  and  may  be  studied  with 
profit  by  all."  —  Portland  Transcript. 

(4) 


PHYSICAL   GEOGRAPHY, 


FOE 


FAMILIES    AND    SCHOOLS. 


PHYSICAL    GEOGRAPHY 


FAMILIES    AND    SCHOOLS. 


R.    M.    ZORNLIN, 


AUTHOR    OF   "RECREATIONS   IN   PHYSICAL   GEOGRAPHY,"    ETC.    ETC. 


REVISED,     WITH     ADDITIONS, 

By    WILLIAM    L.    GAGE, 

LATE  MASTER  OP  THE  TAUNTON  HIGII  school- 
OF  THE. 

^CALIFOfiJ^ 
BOSTON  AND  CAMBRIDGE : 
JAMES    MUNROE    AND    COMPANY 

MDCCCLVI. 


G^6 


Entered  according  to  Act  of  Congress,  in  the  year  1855,  by 

James   M  u  n  r  o  e   and   Company, 

In  the  Clerk's  Office  of  the  District  Court  of  the  District  of  Massachusetts. 


CAMBRIDGE: 
THCRSTON   AND    TORRY,  PRINTERS. 


CONTENTS 


PAGE 

Preface  to  the  English  Edition         ....  ix 

"          "        American    m            xiii 

Note  to  the  Teacher xv 

The  Objects  of  Physical  Geography       ....  1 

The  Earth 2 

Form  of  the  Earth 2 

The  Equator 4 

Diurnal  and  Annual  Motions  of  the  Earth          .        .  6 

Latitude  and  Longitude 9 

Latitude 9 

Circles            10 

Zones 10 

Longitude        ...                 .....  11 

Distribution  of  Land  and  Water 14 

Continents 15 

Islands 15 

Variations  of  the  Surface           .  17 

Mountains 17 

Table  of  Heights  of  Mountains    ....  25 

Plateaus  or  Table  Lands 27 


.111919 


VI  CONTENTS. 

PAGE 

Rain,  Snow,  and  Hail 88 

Plains  or  Lowlands         ......  28 

Valleys 30 

The  Sea-Level        .                 32 

Geology 33 

Rocks "  33 

Earthy  Formations,  &c 34 

Earths 35 

Stratified  Rocks ,36 

Unstratified  Rocks 38 

Volcanic  Regions 39 

Earthquakes 41 

Metallic  Veins 43 

The  Waters  op  the  Globe 45 

Springs      .........  45 

Rivers             50 

Table  of  Lengths  of  Rivers 56 

Lakes 57 

The  Ocean 60 

Tides,  Waves,  and  Currents 68 

TidalWave 68 

Wind  Waves 70 

Currents  of  the  Ocean 71 

The  Atmosphere           .......  75 

Atmospheric  Air 75 

Weight  of  an  Atmosphere 77 

The  Barometer 77 

Winds 79 

Hurricanes 84 

Atmospheric  Moisture 85 

Dew 86 

Mists  and  Fogs 87 

Clouds 88 


CONTENTS. 


Vll 


Climate 

Diversity  of  Climate 

Height  of  Snow  Line 

Isothermal  Lines    .... 

Isochimenal  and  Isotheral  Lines 
Electricity  and  Magnetism 

Electricity 

Terrestrial  Magnetism 
Geographical  Distribution  of  Plants 

Classes  of  Plants     .... 

Nourishment  of  Planls 

Botanical  Regions  .... 

Cultivation  of  the  Cerealia 
Geographical  Distribution  of  Animals 

Departments  of  the  Animal  Kingdom 

Animals  of  the  Old  and  of  the  New  World 

Range  of  Birds  .... 

Geographical  Distribution  of  Man.    . 

Languages  of  the  World    . 

Varieties  of  the  Human  Race 

Conclusion 


Exercises  for  the  Examination  of  Pupils 
Questions  for  Investigation 


Page 
95 
95 
99 
108 
108 
109 
109 
111 
114 
115 
118 
120 
125 
126 
126 
129 
130 

184 
134 
136 
139 
141 
153 


ILLUSTRATIONS. 

Page 

1.  Diagram  illustrative  of  the  Rotundity  of  the  Earth        .        4 

2.  Diagram  illustrative  of  the  Earth's  Orbit       .  .8 

3.  Map  showing  the  Principal   Mountain  Ranges  of  the 

Globe  and  the  Currents  of  the  Ocean       ...       18 

4.  Map  of  the  Rainy  and  Rainless  Districts  of  the  Earth  92 

5.  Height  of  Snow-Line  in  Different  Latitudes   .         .        .101 

6.  Map  of  the  Geographical  Distribution  of  Man     .        .        134 


PREFACE 

TO    THE    ENGLISH    EDITION. 


Physical  Geography  has  of  late  years  become  a 
subject  of  such  general  interest,  and  now  takes  so 
prominent  a  place  among  popular  sciences,  that  some 
acquaintance  with  its  aim  and  the  views  it  unfolds 
may  be  considered  as  one  of  the  requirements  of  edu- 
cation. To  facilitate  the  attainment  of  this  knowledge 
is  the  design  of  the  present  little  work,  in  which  the 
subject  is  placed  before  the  reader  in  familiar  lan- 
guage and  in  a  concise  form,  thus  adapting  it  not  only 
for  the  scholar,  but  also  for  the  parent  and  teacher, 
and  for  all  who,  from  previous  inattention  to  this 
branch  of  knowledge,  may  be  desirous  of  forming  a 
ready  acquaintance  with  the  leading  principles  of  the 
science. 


X  PREFACE. 

Physical  Geography  owes  its  present  state  of  for- 
wardness to  the  combined  observations  of  numerous 
individuals ;  and  perhaps  may  be  considered  as  dating 
its  great  advance  from  the  era  of  the  general  peace  of 
1815  ;  for  it  has  only  been  subsequent  to  the  cessation 
of  war,  that  scientific  men  of  various  nations  have  ob- 
tained free  access  to  different  stations  on  the  earth's 
surface,  where  observations  have  been  successfully 
carried  on ;  and  it  is  by  the  mutual  interchange  of 
information  thus  gathered,  that  a  large  portion  of 
our  knowledge  of  Physical  Geography  has  been  ac- 
quired. 

We  have  said  that  this  science  owes  its  great  prog- 
ress to  the  combined  observations  of  numerous  indi- 
viduals ;  —  we  may  also  add,  that  it  invites  its  student 
to  observe,  to  give  his  attention  to  all  that  its  passing 
around  him  in  the  natural  world,  and  to  verify  for 
himself,  as  far  as  circumstances  will  admit,  the  truth 
of  the  data  thus  presented  to  his  view.  He  may  even 
lend  his  aid  to  the  furtherance  of  this  science.  In- 
stances are  not  wanting,  both  in  our  own  day  and  in 
former  times,  of  individuals  from  every  class  of  society 
raising  themselves  to  eminence  by  the  pursuit  of 
science  ;  and  the  path  is  open  to  all.  The  inhabitant 
of  the  country  may,  doubtless,  in  this  respect  possess 


PREFACE.  XI 

greater  advantages  than  the  dweller  in  crowded  cities  ; 
he  may  take  note  of  the  minerals  and  plants  in  his  own 
immediate  neighborhood,  or  may  devote  his  attention 
to  the  habits  of  birds  and  insects,  and  by  recording  his 
observations  may  contribute  his  quota  to  the  general 
mass  of  knowledge.  But  the  dweller  in  towns  may 
also  perform  his  part :  he  may  observe  the  ever-vary- 
ing clouds,  the  temperature,  the  climate  of  the  place 
of  his  abode.  He,  too,  may  enjoy  opportunities  denied 
to  the  other,  of  ready  access  to  works  of  travels,  and 
thus  be  enabled  to  trace  the  application  of  the  knowl- 
edge he  has  acquired  to  all  parts  of  the  globe.  Had 
our  limits  permitted,  we  would  gladly  have  attempted 
this  application  in  the  present  little  treatise  ;  but  having 
already  in  a  former  work,*  with  this  especial  object  in 
view,  carried  our  friends  over  the  various  regions  of 
the  earth,  we  must  now  content  ourselves  with  tracing 
the  Outlines  of  Physical  Geography,  trusting  that 
these  will  be  found  of  sufficient  interest  to  induce  our 
readers  to   pursue  the  subject  into  its  more   minute 

details. 

R.  M.  Z. 

*  Recreations  in  Physical  Geography. 


PREFACE 

TO  THE   AMERICAN  EDITION. 


In  the  preparing  of  small  school  books,  the  English 
have  an  unquestionable  superiority  over  us.  Such 
treatises  with  them  have  the  great  merit  of  comprehen- 
siveness, and  avoid  both  childish  diffuseness  and 
merely  superficial  views.  This  little  work,  which  we 
take  pleasure  in  introducing  to  American  teachers,  will 
suitably  illustrate  this.  While  its  range  is  very  broad  ; 
while  we  are  now  lifted  to  the  clouds,  and  anon  carried 
far  into  the  depths  beneath  our  feet ;  transported  in  a 
moment  from  ocean  to  ocean  and  from  shore  to  shore, 
initiated  into  the  manifold  secrets  of  nature,  and  taught 
on  every  side  the  greatness  and  the  wisdom  and  the 
love  of  the  Creator  and  Father  of  us  all,  we  see  the 
chain  which  binds  together  all  the  sciences  and  makes 
them  one. 


XIV  PREFACE. 

And  in  the  study  of  this  comprehensive  science  of 
sciences,  which  is  termed  in  one  word  Physics,  we  on 
this  side  of  the  Atlantic  have  made  bjut  little  advance- 
ment. Still,  the  impulse  which  Maury  and  Guyot, 
Fremont  and  Agassiz  and  Bache  have  given  to  this 
department  of  human  knowledge,  will  not  lose  its  force 
till  it  is  felt  in  our  schools.  The  day  is  not  distant 
when  the  study  of  Physical  Geography  will  not  only 
escape  neglect,  but  will  take  the  same  rank  in  Ameri- 
can that  it  does  in  English  schools.  We  hope  that  this 
little  treatise  will  be  the  means  in  part  of  accomplish- 
ing this  great  end,  and  that  in  opening  to  the  young 
the  riches  of  this  science,  it  may  tempt  to  a  deeper 
search  than  this  work  can  afford.  Those  who  may 
have  acquired  some  interest  in  the  fascinating  study  of 
Physics,  can  gratify  their  curiosity  by  consulting  the 
pages  of  Mrs.  Somerville,  Guyot,  Wittich,  Murray,  and 
the  larger  work  by  the  author  of  this  treatise,  while  the 
most  mature  mind  may  reserve  its  strength  for  the 
broad  generalizations  of  Humboldt's  Kosmos. 

W.  L.  G. 

Boston,  October,  1855. 


NOTE 

TO    THE    TEACHER 


This  work  can  be  used  by  scholars  of  ordinary 
abilities  from  twelve  to  eighteen  years  of  age. 
With  the  youngest  class  who  may  have  it,  let 
the  teacher  invent  very  numerous  questions;  to 
scholars  of  an  older  age,  those  at  the  close  of 
the  volume  will  suggest  the  contents  of  sen- 
tences, and  in  some  cases  of  paragraphs ;  the 
pupils  of  the  first  class  will  need  no  questions, 
but  should  give  a  summary  of  the  contents  of 
the  lesson,  omitting  no  fact,  however  unimpor- 
tant, yet  not  committing  the  words  of  the  book 
to  memory  more  than  need  be. 

Have  the  locality  of  every  place  mentioned  in 
the  book  known  and  recited. 


XVI  NOTE    TO    THE    TEACHER. 

Have  the  meaning  of  all  important  words 
given,  and  accustom  the  scholars  to  give  full 
explanations  of  phenomena  like  the  currents, 
winds,  &c.  Accustom  the  pupils  to  a  habit  of 
getting  collateral  information  from  all  sources, 
and  expressing  it  freely  in  the  class-room. 

Have  the  work  known  with  perfect  accuracy 
before  it  is  laid  aside,  that  the  facts  contained  in 
it  may  be  remembered  through  life. 


V  OF  THE 

UNIVERSITY 

Palifcb^ 


PHYSICAL   GEOGRAPHY 


I.  THE  OBJECTS  OF  PHYSICAL  GEOGRAPHY. 

Physical  Geography,  or  in  other  terms.  Na- 
tural Geography,  consists  of  a  description  of 
the  Earth  we  inhabit,  and  directs  our  attention 
to  its  structure,  to  the  waters  on  its  surface,  to  its 
atmosphere,  to  its  various  animal,  vegetable  and 
mineral  productions,  and  to  the  laws  by  which 
these  are  governed. 

It  is  called  Physical  or  Natural  Geography, 
because  it  considers  the  Earth  under  its  natural 
features,  that  is,  according  to  the  nature  imparted 
to  it  by  its  Almighty  Maker,  and  not  in  reference 
to  any  artificial  divisions  made  by  man  into 
kingdoms  and  states.  We  are  thus  led  to  regard 
the  Earth  as  one  great  whole ;  and  regions  are 
determined  by  natural  conditions,  such  as  the 
climate  or  temperature  of  any  portion  of  the 
Earth's  surface,  the  prevalence  or  absence  of 
particular  species  of  plants,  &c. 
1 


4  PHYSICAL    GEOGRAPHY. 

Physical  Geography  is  a  science  of  great 
utility,  because  it  makes  us  acquainted  with 
much  that  tends  to  man's  benefit  and  prosperity. 
It  also  forms  a  very  gratifying  pursuit,  for  it 
presents  us  with  numberless  highly  interesting 
facts  in  the  natural  world,  which  might  other- 
wise pass  unheeded,  and  it  displays  to  our  view 
the  wisdom  and  goodness  of  the  great  Creator 
of  the  Universe. 


II.  THE  EARTH. 


The  Earth  belongs  to  a  group  or  system  of 
bodies  termed  planets,  which  revolve  round  the 
Sun,  from  which  they  derive  both  light  and  heat. 

The  Earth  is  of  a  spherical  or  globular  form. 
A  sphere  is  a  perfectly  round  body  :  this  the 
Earth  is  not,  being  somewhat  flattened  (not  un- 
like the  usual  shape  of  an  orange)  at  the  ex- 
tremities of  its  axis,  which  are  called  the  north 
and  south  poles.  The  earth  is  accordingly  not  a 
perfect  sphere,  and  is  termed  a  spheroid. 

This  spheroid  is  called  oblate,  because  it  re- 
volves about  its  shortest  diameter.  The  peculiar 
shape  of  the  Earth  is  that  which  a  soft  globe 


THE    EARTH. 


assumes  when  put  into  rapid  motion ;  and  the 
Earth  is  supposed  to  have  been  once  in  a  soft 
state. 

The  spherical  form  or  rotundity  of  the  Earth 
is  proved  by  ships  sailing  round  the  globe.  It  is 
well  known  that  Captain  Cook  and  a  host  of 
other  navigators  have,  by  steering  in  either  an 
eastward  or  westward  direction  (as  nearly  as  the 
general  arrangement  of  land  and  water  will  per- 
mit), ultimately  returned  to  the  same  point  from 
which  they  started. 

The  globular  form  of  the  Earth  is  also  proved 
by  the  appearance  presented  on  the  surface  of 
the  ocean.  If  the  Earth  were  a  flat  plain,  the 
distances  would  seem  misty  and  ill-defined,  in- 
stead of  which  a  sharp,  clear,  well-marked  line, 
called  the  horizon,  extends  all  round  a  vessel  in 
the  broad  open  sea,  in  the  form  of  a  circle,  of 
which  the  vessel  forms  the  centre.  The  undula- 
tions of  the  dry  land,  and  the  various  objects  on 
its  surface,  prevent  us  from  observing  this  with 
any  degree  of  certainty  in  the  interior  of  a  coun- 
try ;  but  if  we  stand  on  the  sea  shore,  we  may 
notice  that  the  surface  of  the  ocean  is  terminated 
by  a  clear  distinctly-marked  line,  which  consti- 
tutes the  visible  horizon. 

If  while  we  are  on  the  borders  of  the  ocean,  a 
vessel  should  put  out  to  sea,  a  most  excellent 


4  THE    EARTH. 

opportunity  will  be  afforded  us  of  observing  the 
globular  form  of  the  Earth,  by  watching  this  ves- 
sel as  it  recedes  from  the  shore.  The  visible 
horizon  may  be  considered  as  extending  to  the 
distance  of  about  30  miles  from  a  person  stand- 
ing on  the  beach.  As  the  vessel  recedes  from 
the  shore,  it  will  diminish  in  size,  but  the  whole 
will  be  visible  until  it  reaches  this  water  line. 
When  it  has  passed  this  line,  though  the  masts 
and  sails  will  still  remain  in  view,  the  hull  of  the 
ship  will  be  below  the  horizon,  the  portion  of  the 
ocean  on  which  it  is  sailing  being  concealed  from 
the  spectator  by  the  globular  form  of  the  Earth, 
and  at  length  the  whole  will  be  lost  to  his  view. 


Thus,  if  the  spectator  were  to  stand  on  the 
sea  shore  sh,  the  visible  horizon  would  extend  on 
a  level  with  the  line  h  z  n,  and  when  the  vessel 
had  passed  the  portion  of  the  sea  to  which  that 
line  extends  at  n,  it  would  be  descending  what 
to  the  spectator  at  s  forms  the  other  side  of  the 
globular-shaped  earth  and  the  waters  on  its  sur- 


face. 


The  Earth,  or  globe,  is  divided  into  two  equal 
parts  by  an  imaginary  line  called  the  equator,  or 


THE    EARTH. 


equinoctial  line,  the  upper  portion  (or  half-sphere) 
of  the  globe  being  distinguished  as  the  northern 
hemisphere,  and  the  lower  portion  as  the  southern 
hemisphere. 

Maps  of  the  world  are  frequently  divided  into 
two  circular  portions,  called  the  eastern  and  west- 
em  hemispheres.  These  have  no  marked  division 
like  that  of  the  equator,  which  extends  from  east 
to  west  across  these  hemispheres,  but  they  are 
useful  as  a  mode  of  representing  the  form  of  a 
globular  body  like  the  Earth  on  a  flat  surface, 
and  also  as  conveying  an  idea  of  the  two  great 
divisions  of  land  on  the  face  of  the  Earth. 

The  circumference  of  the  Earth,  that  is,  its 
girth  at  the  equator,  where  it  is  of  greatest  size, 
is  nearly  25,000  miles.  Its  diameter,  or  the  meas- 
ure of  its  width  through  the  centre  at  that  line,  is 
rather  less  than  one-third  of  its  circumference,  or 
about  7926  miles.  In  consequence  of  its  being 
in  some  degree  flattened  at  the  poles,  its  diameter 
from  north  to  south  is  about  26  miles  less,  or 
7900  miles.  The  diameter  may  be  stated,  in 
round  numbers,  at  8000  miles ;  and  the  radius, 
or  distance  from  the  centre  to  the  surface,  at 
4000. 

'  The  Earth  turns  on  its  axis ;  though  this  axis 
is  only  an  imaginary  fine  passing  through  the 
Earth  from  pole  to  pole.     This  motion  is  well 


6  THE    EARTH. 

represented  in  the  ordinary  school  globes,  and 
may  be  imitated  with  an  apple  or  a  ball.  In 
consequence  of  this  turning  motion,  called  the 
rotation  of  the  Earth,  all  parts  of  its  surface  are 
in  succession  presented  to  the  sun's  rays;  and 
since  the  motion  takes  place  from  west  to  east, 
the  Earth  always  meets  or  turns  to  the  sun  in 
its  eastern  parts,  which  gives  the  appearance  of 
the  sun's  rising  in  that  quarter,,  the  variation  to 
the  north  or  south  of  east  being  dependent  on 
its  relative  position  to  the  sun  at  different  sea- 
sons of  the  year.  This  motion  of  rotation,  called 
the  Earth's  diurnal  motion,  is  completed  in  about 
24  hours  (correctly  speaking,  23  hours  56  min- 
utes 4  seconds),  which  constitutes  a  natural  day. 
The  rate  of  the  Earth's  rotary  motion  at  the 
equator  exceeds  1000  miles  an  hour;  but  the 
velocity  of  rotation  diminishes  as  we  recede  from 
that  line,  in  accordance  with  the  Earth's  dimin- 
ished circumference. 

While  the  Earth  is  thus  continually  turning 
on  its  axis,  it  has  also  a  progressive  or  onward 
motion  in  its  orbit,  that  is,  its  path  round  the  sun. 
The  length  of  this  orbit  has  been  estimated  at 
about  600  millions  of  miles,  and  the  rate  of  the 
Earth's  motion  in  its  orbit  to  exceed  68,000  miles 
in  an  hour,  or  about  1000  miles  in  a  second. 
The  Earth's  orbit  or  path  is  not  perfectly  cir- 


THE    EARTH.  7 

cular,  but  elliptical*  in  consequence  of  which  the 
Earth  is  not  always  at  the  same  distance  from 
the  sun,  but  its  average  distance  is  95  millions 
of  miles.  The  Earth  completes  this  revolution 
round  the  sun  in  365  days  and  6  hours,  which 
constitute  a  year. 

The  Earth,  while  performing  its  annual  course 
round  the  sun,  has  not  its  axis  placed  at  right 
angles  with  the  line  it  pursues,  but  in  an  oblique 
or  slanting  direction ;  the  consequence  of  which 
is,  that  the  earth  presents  to  the  action  of  the  sun's 
rays  a  greater  portion  of  the  northern  hemisphere 
during  one  half  of  the  year,  and  a  greater  portion 
of  the  southern  hemisphere  during  the  other  half 
of  the  year.  The  period  at  which  any  particular 
portion  of  the  Earth's  surface  is  turned  most 
directly  towards  the  sun  constitutes  mid-summer 
at  that  particular  locality;  and  it  will  at  the 
same  time  be  mid-winter  at  the  opposite  portion 
of  the  globe.  Thus,  when  it  is  mid-summer  in 
the  British  Isles,  it  will  be  mid-winter  at  the 
little  island  of  Antipodes,  not  far  from  New  Zea- 
land :  when  it  is  mid-summer  in  New  England, 

*  An  ellipse  is  an  oval  figure  so  shaped,  that  the  sum  of  the 
two  distances  of  each  point  of  the  curve  from  two  points  within, 
called  foci,  is  always  the  same.  The  Sun's  place  is  a  focus  of 
each  planetary  orbit.  An  ellipse  may  be  drawn  with  a  string, 
two  pins,  and  a  pencil. 


O  THE    EARTH. 

it  is  mid-winter  in  the  northern  part  of  the  Aus- 
tral Ocean.  In  the  figure  below,  the  orbit  is 
made  much  more  elliptical  than  it  is  in  reality, 
and  the  Sun,  which  belongs  in  one  of  the  foci, 
is  put  at  the  centre.  At  each  equinox,  a  hemis- 
phere is  shown  which  reaches  both  the  poles; 
but  at  the  vernal  equinox  the  illuminated  half 
appears,  at  the  autumnal  the  dark  half;  the 
globe  in  the  latter  case  being  between  the  Sun 
and  the  eye.  Observe  that  the  lines  n  s,  repre- 
senting the  earth's  axis,  always  remain  parallel 
to  each  other. 


20th  March,  1855. 


23d  September,  1855. 


LATITUDE    AND    LONGITUDE. 


HI.  LATITUDE  AND  LONGITUDE. 

The  globe  or  earth,  for  the  convenience  of 
measurement,  is  divided  into  degrees  of  latitude 
and  longitude ;  these  degrees  being  indicated  by 
this  sign,  °. 

Latitude  is  marked  by  lines  or  circles  running 
parallel  with  the  equator,  each  hemisphere  being 
divided  into  ninety  degrees  between  the  equator 
and  the  north  and  south  poles.  The  reckoning 
commences  from  the  equator,  and  is  distinguished 
as  north  and  south  latitude.  The  latitude  of  any 
place  is  therefore  determined  by  its  distance 
north  or  south  of  that  line.  Thus  London  is  in 
north  latitude  51^°.  The  Cape  of  Good  Hope 
is  in  south  latitude  35°.  Any  place  situated  on 
or  near  the  equator  is  said  to  be  in  a  low  lati- 
tude ;  any  place  near  the  Arctic  circle  to  be  in  a 
high  latitude.  Thus,  Sierra  Leone  is  in  the  low 
latitude  of  8£°  N.,  Archangel  in  the  high  lati- 
tude of  64^°  N. 

Each  degree  is  divided  into  sixty  minutes, 
marked  thus, ' ;  the  latitude  of  London  being 
51°  30' ;  that  is,  fifty-one  degrees,  thirty  minutes. 
The  number  of  miles  comprised  in  a  degree  of 
latitude  is  nearly  seventy. 


10  LATITUDE    AND    LONGITUDE. 

Places  situated  in  the  same  degree  of  latitude 
are  said  to  be  on  the  same  parallel.  Thus,  Nor- 
wich and  Berlin  are  on  the  same  parallel  of  lati- 
tude, about  N.  lat.  52}  degrees. 

The  globe  has  a  further  division,  also  running 
parallel  with  the  equator,  marked  by  four  circles, 
called  the  Arctic  circle,  the  Antarctic  circle,  the 
Tropic  of  Cancer,  and  the  Tropic  of  Capricorn. 
The  tropics  are  situated  at  the  distance  of  23^° 
north  and  south  of  the  equator ;  the  Arctic  and 
Antarctic  circles,  23£°  from  the  north  and  south 
poles,  or  in  north  and  south  latitude  66J  de- 
grees. 

These  circles  divide  the  earth  into  five  zones, 
or  b^lts,  the  torrid  zone,  the  two  temperate  zones, 
and  the  two  frigid  zones.  The  torrid  zone,  so 
called  from  the  heat  of  that  portion  of  the  earth 
which  it  includes,  extends  to  23^°  on  each  side 
of  the  equator ;  that  is,  to  the  tropic  of  Cancer  on 
the  north,  and  the  tropic  of  Capricorn  on  the 
south,  of  the  equator.  This  zone  is  called  inter- 
tropical, from  its  lying  between  the  tropics.  The 
northern  temperate  zone  extends  from  the  tropic 
of  Cancer  to  the  Arctic  circle,  and  the  southern 
temperate  zone  from  the  tropic  of  Capricorn  to 
the  Antarctic  circle ;  that  is,  respectively  from 
north  and  south  latitude  23^°  to  north  and  south 
latitude  66£°.     The  frigid  zones  extend  from  the 


LATITUDE    AND    LONGITUDE.  11 

Arctic  and  Antarctic,  or  polar,  circles,  to  the 
north  and  south  poles ;  that  is,  from  north  and 
south  latitude  66^°  to  north  and  south  latitude 
90°.  They  are  called  frigid,  from  the  cold  tem- 
perature which  prevails  in  those  regions. 

The  Earth's  surface  is  also  crossed  by  imagin- 
ary lines  passing  from  north  to  south  through 
the  poles ;  these  are  called  meridians.  The 
longitude  of  any  place  is  determined  by  its  dis- 
tance (reckoned  in  degrees)  eastward  or  west- 
ward from  any  given  meridian.  In  Britain, 
longitude  is  calculated  from  the  meridian  of 
London  (or,  more  correctly  speaking,  of  the  Royal 
Observatory  at  Greenivich).* 

For  the  measurement  of  longitude,  the  equa- 
tor is  divided  into  360  parts  or  degrees  J  the  same 
division  into  360  degrees  being  maintained  in  all 
parallels  of  latitude,  though,  since  the  girth  or 
circumference  of  the  earth  diminishes  as  we  re- 
cede from  the  equator,  degrees  of  longitude  do 
not  contain  so  many  miles  in  high  as  in  low 


*  For  convenience,  the  meridian  of  London  is  assumed  as  the 
line  from  which  navigators  reckon  their  longitude,  yet  in  nation- 
al calculations  it  is  customary  to  make  the  capital  of  the  country 
the  point  from  which  to  determine  longitude.  Thus,  in  America, 
we  have  the  meridian  of  Washington,  the  Prussians  use  the 
meridian  of  Berlin,  the  Austrians  that  of  Vienna,  &c. 


12  LATITUDE  AND  LONGITUDE. 

latitudes,  which  will  be  evident  from  the  follow- 
ing table :  —   w 

LATITUDE.  MILES. 

0° 68| 

10° 67£ 

20° 64| 

30° 59£ 

40° 52£ 

50° 44 

60° 341 

70° 23^ 

80° 12" 

90° 0 

We  thus  perceive  that  a  degree  of  longitude  at 
the  equator  contains  nearly  69  miles,  but  in  lati- 
tude 80°,  only  12  miles,  and  at  the  poles  it  di- 
minishes to  nothing. 

Longitude  is  ordinarily  reckoned  east  and 
west  from  the  meridian  of  Greenwich  to  the 
opposite  point  of  the  globe's  circumference ; 
there  being  thus  180  degrees  of  east  longitude, 
and  180  degrees  of  west  longitude.  All  places 
eastward  of  Greenwich  are  reckoned  as  being 
situated  in  east  longitude ;  and  all  places  west- 
ward of  Greenwich  as  being  situated  in  west 
longitude. 

Places  situated  in  the  same  degree  of  longi- 
tude are  said  to  be  on  the  same  meridian*  The 
term  meridian  is  used,  because  the  sun  will  be 

*  Derived  from  the  Latin  meridies,  mid-day. 


LATITUDE    AND    LONGITUDE.  13 

at  its  greatest  height,  or  it  will  be  mid-day,  at  the 
same  time  at  all  places  in  the  same  longitude. 
Thus,  Bordeaux  is  on  the  same  meridian  as 
London,  and  therefore  it  will  be  noon,  or  mid- 
day, at  the  same  time  at  both  places.  It  will  be 
noon  earlier  than  in  London  at  all  places  situ- 
ated to  the  eastward  of  that  meridian,  or  in  east 
longitude,  and  later  at  all  places  situated  in  west 
longitude.  The  sun  will  rise  rather  sooner  at 
Berlin,  and  much  later  at  New  York,  than  in  Lon- 
don. At  Calcutta,  which  is  situated  in  east  longi- 
tude 88°,  it  will  be  noon  when  it  is  a  little  after 
sLx  in  the  morning  in  London ;  and  at  the  Feejee 
Islands,  in  the  Pacific  Ocean,  which  are  situated 
nearly  at  the  point  where  east  and  west  longi- 
tude meet,  it  will  be,  noon,  or  mid-day,  when  it 
is  midnight  in  London.  The  sun  is  said  to  be 
on  the  meridian  at  mid-day :  it  is  then  due  south, 
and  at  its  greatest  altitude,  or  height,  for  that  par- 
ticular day. 

As  the  earth  revolves  on  its  axis  once  in  twenty- 
four  hours,  the  sun  passes  over  one  twenty-fourth 
of  360°,  or  15°,  in  one  hour.  The  difference  of 
time  between  two  places  can  be  easily  calculated 
by  dividing  the  difference  of  their  longitude  by 
1").  This  will  give  the  number  of  hours  and 
the  fractional  part  of  an  hour ;  the  latter  can  be 
reduced,  if  necessary,  to  minutes  and  seconds. 


14  DISTRIBUTION    OF    LAND    AND    WATER. 

This  difference  must  of  course  be  added  to  ob- 
tain the  time  of  a  place  east  of  a  given  meridian ; 
subtracted  for  a  place  west  of  it. 


IV.  DISTRIBUTION  OF  LAND  AND  WATER. 

The  land  does  not  occupy  much  more  than 
one-fourth  of  the  entire  surface  of  the  globe,  the 
remainder  being  covered  by  the  waters  of  the 
ocean.  Thus,  the  extent  of  the  whole  surface 
being  estimated  at  nearly  197  million  square 
miles,  the  space  occupied  by  land  is  considered 
to  be  about  52  million  square  miles,  and  that 
covered  by  the  waters  of  the  ocean  about  145 
million  square  miles. 

The  proportion  of  land  is  much  greater  in  the 
northern  than  in  the  southern  hemisphere;  it 
having  been  computed  that  in  the  northern 
hemisphere  the  land  occupies  about  38  million 
square  miles,  and  the  waters  of  the  ocean  rather 
above  60  million,  whilst  in  the  southern  hemi- 
sphere the  land  has  been  supposed  not  to  occupy 
quite  14  million  square  miles,  and  the  waters  of 
the  ocean  to  cover  an  area  of  about  85  million 
square  miles.  The  recent  discoveries  of  large 
tracts  of  land  in  the  Antarctic  regions,  the  extent 


DISTRIBUTION    OF    LAND    AND    WATER.  15 

of  which  is  yet  unknown,  render  the  correctness 
of  the  latter  computation  more  than  doubtful. 

The  dry  land  is  usually  considered  under  two 
principal  heads :  continents  and  islands. 

The  term  continent  has  been  commonly  ap- 
plied to  four  portions  of  the  earth,  and  it  is  cus- 
tomary to  speak  of  the  continents  of  Europe, 
Asia,  Africa,  and  America ;  but,  more  correctly 
speaking,  there  are  only  two  continents,  dis- 
tinguished as  the  Eastern  and  Western  Conti- 
nents. 

The  Eastern  Continent,  called  also  the  Old 
World  —  because  it  has  formed  the  abode  of 
civilized  man  from  the  earliest  period  of  histori- 
cal records  —  comprehends  Europe,  Asia,  and 
Africa.  The  Western  Continent,  called  the 
New  World  —  because  it  has  only  been  known 
to  Europeans  since  its  discovery  by  Columbus 
in  1492  —  includes  the  whole  of  America. 

These  two  vast  continents  are  in  fact  only 
larger  islands,  being  surrounded  on  all  sides  by 
water ;  but  since  large  surfaces  of  land  differ  in 
their  climate  and  natural  productions  from  islands 
of  smaller  size,  it  is  desirable  to  make  this  dis- 
tinction, and  to  treat  of  these  two  grand  divisions 
of  the  earth  as  continents. 

The  islands  on  the  earth's  surface  are  of  vari- 
ous dimensions,  and  of  various  elevations  above 


16  DISTRIBUTION    OF    LAND    AND    WATER. 

the  sea.  The  immense  basin  which  is  occupied 
by  the  waters  of  the  ocean  is  apparently  greatly 
diversified  in  its  surface ;  in  some  parts  deep  de- 
pressions or  submarine  valleys  occurring,  whilst 
in  others  partially-immersed  mountains  rise  above 
the  waters,  forming  islands  of  larger  or  smaller 
extent,  and  in  some  instances  mere  insulated 
rocks. 

Australia  is  by  far  the  largest  island  on  the 
face  of  the  globe,  its  greatest  length  being  about 
2500  miles,  and  its  greatest  width  about  1800 
miles.  This  vast  island  is  sometimes  called  a 
continent,  but  is  more  correctly  included  among 
the  Islands.  Australia,  in  conjunction  with 
New  Zealand  and  the  numerous  smaller  islands 
with  which  the  Pacific  Ocean  is  studded,  is 
sometimes  regarded  under  the  distinct  appella- 
tion of  Oceanica. 

On  referring  to  the  map  of  the  world,  we  shall 
perceive  that  the  form  in  which  the  dry  land  is 
arranged  differs  greatly  in  the  Old  and  New 
Continents ;  in  the  Old  Continent  the  principal 
extension  being  from  east  to  west,  whilst  in  the 
New  it  is  from  north  to  south. 

In  the  Old  Continent  continuous  straight  lines 
may  be  drawn  for  immense  distances  from  south- 
west to  north-east,  over  vast  tracts  of  dry  land, 
without  encountering  any  great  expanse  of  water. 


MOUNTAINS.  17 

Thus,  a  line  drawn  from  Cape  Verd  in  West- 
ern Africa,  crossing  the  Isthmus  of  Suez,  and 
extending  to  Quanlin  on  the  borders  of  the 
Pacific  Ocean,  (situated  a  little  to  the  north  of 
the  Japan  isles,)  would  pass  over  a  tract  of  dry- 
land no  less  than  9750  miles  in  length.  The 
New  Continent,  on  the  other  hand,  has  its  great- 
est length  from  north  to  south,  extending  through 
120  degrees  of  latitude. 


V.  VARIATIONS  OF  THE  SURFACE. 

The  dry  land  is  elevated  into  mountains  and 
highlands,  spread  forth  in  plains,  or  depressed  in- 
to valleys,  all  varying  in  extent  and  in  elevation 
above  the  level  of  the  sea. 

Mountains  are  met  with  in  ranges  and  groups, 
or  as  isolated  mountains. 

Mountain  ranges,  or  continuous  ridges  of 
mountains,  not  unfrequently  rising  to  a  great 
elevation  above  the  adjacent  districts,  sometimes 
extend  over  large  tracts  of  country,  the  length  of 
the  principal  ridge  being  usually  much  greater 
than  its  width.  In  many  instances  we  find  that 
a  general  correspondence  may  be  traced  between 
the  direction  of  mountain  ranges  and  the  form  of 
2 


16 


VARIATIONS    OF    THE    SURFACE. 


MOUNTAINS.  19 

the  regions  they  traverse,  as  will  be  evident  from 
a  reference  to  the  accompanying  map,  the  black 
lines  on  which  indicate  the  principal  mountain 
ranges. 

Thus,  the  greatest  extension  of  the  Old  World 
is  from  east  to  west,  and  a  vast  and  nearly  con- 
tinuous line  of  mountains  extends  across  the 
whole  continent  in  that  direction.  The  greatest 
length  of  the  New  World  is  from  north  to  south, 
and  in  that  continent  a  mighty  mountain  range 
stretches  from  its  northern  to  its  southern  ex- 
tremity. 

The  nearly  continuous  line  of  mountains  which 
may  be  traced  across  the  whole  of  the  Old  Con- 
tinent, from  the  very  shores  of  the  Atlantic  to 
those  of  the  Pacific  Ocean,  commences  in  West- 
ern Europe  with  the  Pyrenees,  with  which  the 
Sierras,  or  mountain  ranges  of  Spain,  are  con- 
nected. The  valley  of  Languedoc  forms  an 
interruption  to  the  grand  chain  of  mountains, 
intervening  as  it  does  between  the  Pyrenees  and 
the  comparatively  low  range  of  the  Cevennes, 
which  extend  nearly  across  the  south-eastern 
part  of  France,  and  which  may  be  considered 
as  forming  the  next  prolongation  of  the  line. 
To  this  range  succeeds  the  mighty  moun- 
tain system  of  the  Alps,  covering  a  large  ex- 
tent of  surface  in  Switzerland  and  some  of  the 


20 


VARIATIONS    OF    THE    SURFACE. 


adjacent  territories,  and  containing  the  most  ele- 
vated summits  in  Europe.  The  mountains  of 
Germany  and  Bohemia  do  not  attain  any  great 
altitude ;  these  are  succeeded  by  the  Carpa- 
thian mountains,  which  skirt  the  north-eastern 
borders  of  Hungary.  From  the  last  range,  and 
also  from  the  Alps,  mountain  branches  extend 
into  Turkey,  where  the  Balkan  range  carries  the 
great  line  to  the  shores  of  the  Euxine  or  Black 
Sea,  and  to  the  confines  of  Europe.  In  Asia 
Minor  and  Syria,  it  is  continued  by  the  ranges 
of  Taurus,  Libanus,  and  Anti-Libanus,  and  from 
these  by  the  mountains  of  Armenia  and  Per- 
sia, including  the  Elburz  range  which  skirts 
the  southern  shores  of  the  Caspian  Sea,  to 
the  borders  of  India.  The  Caucasian  moun- 
tains, situated  to  the  westward  of  the  Caspian 
Sea,  appear  rather  as  a  detached  group.  At 
the  borders  of  India  we  arrive  at  a  grand 
mountain  knot,  the  Hindoo  Koh  or  Coosh,  from 
which  mountain  ranges  diverge  to  the  north 
and  to  the  south,  as  well  as  to  the  east  and  west. 
The  grand  line  is  prolonged  to  the  eastward  by 
the  Kuenlun  and  the  Himalaya  mountains,  the 
latter  stupendous  range,  which  separates  Hindo- 
stan  from  Tibet,  containing  the  loftiest  known 
summits  on  the  face  of  the  globe.  The  Himalaya 
mountains  take  a  south-easterly  course,  and  ter- 


MOUNTAINS.  21 

minate  at  the  river  Brahmapootra,  whence  the 
line  is  continued  by  ranges  of  mountains  hitherto 
little  explored,  and  finds  its  termination  in  the 
mountains  of  China,  which  carry  it  to  the  shores 
of  the  Pacific  Ocean.  The  Kuenlun  mountains 
skirt  the  north  of  Tibet  and  are  prolonged  by  the 
Khin-gcui  range,  which,  turning  northward,  is 
again  prolonged  by  other  ranges,  running  in  a  line 
nearly  parallel  with  the  eastern  coast  of  Asia,  and 
extending  almost  to  its  most  northerly  limits. 

The  vast  mountain  system  which  extends  from 
the  northern  to  the  southern  extremity  of  the 
New  World,  presents  a  far  more  striking  instance 
of  the  correspondence  between  the  direction  of 
mountain  ranges  and  the  regions  they  traverse. 
The  Racky  Mountains  extend  from  the  borders 
of  the  Arctic  Seas  to  the  Isthmus  of  Panama, 
their  general  course  agreeing  very  closely  with 
that  of  the  western  coast  line  of  North  America. 
This  vast  range  becomes  twice  depressed  in  Cen- 
tral America,  but  soon  regains  more  than  its 
former  height,  and  under  the  name  of  the  Andes 
extends  along  the  whole  of  Western  South 
America,  its  direction  corresponding  very  nearly 
with  that  of  the  coast.  The  Andes  contain  a 
va-t  assemblage  of  elevated  summits,  a  great 
number  of  which  are  covered  with  perpetual 
snow,  although  some  of  them  are  situated  in  the 


22  VARIATIONS    OF    THE    SURFACE. 

hottest  regions  of  the  globe.  Numerous  active 
volcanoes  also  occur  among  the  Andes.  As 
they  approach  the  southern  extremity  of  the  con- 
tinent, these  mountains  lose  their  great  elevation, 
and  finally  terminate  in  Cape  Horn,  1860  feet 
above  the  level  of  the  sea.  The  course  of  the 
Alleghany  mountains  corresponds  nearly  with 
that  of  the  eastern  coast  of  the  United  States. 

The  character  of  general  correspondence  be- 
tween the  direction  of  mountain  ranges  and  the 
form  of  the  regions  they  traverse,  is  often  very 
observable  in  smaller  portions  of  land,  such  as 
peninsulas  and  islands.  Thus,  the  form  of  Italy 
corresponds  closely  with  that  of  the  direction 
taken  by  the  Apennines,  which  extend  through 
the  whole  of  that  peninsula.  The  form  of  Scan- 
dinavia (Sweden  and  Norway)  agrees  with  the 
direction  of  the  Dofrefeld  mountains,  which  tra- 
verse that  territory  from  north  to  south.  Among 
islands,  Corsica,  Madagascar,  Cuba,  and  Jamai- 
ca, afford  striking  instances  of  the  correspondence 
of  mountain  ranges  with  the  form  of  the  land 
along  which  they  extend. 

Mountain  ranges  present  some  of  the  grandest 
natural  scenes  on  the  face  of  the  globe.  The  form 
of  ridges  and  summits  is  much  influenced  by  the 
nature  of  the  rocks  of  which  they  are  composed. 
In  some  regions,  the  mountain  tops  are  rounded, 


MOUNTAINS.  23 

like  the  limestone  summits  among  the  Apen- 
nines ;  in  others,  serrated  or  saw-shaped,  like  the 
slaty  Sierras  of  Spain ;  in  others,  they  rise  in 
peaks  or  horns,  like  Mont  Blanc  and  *Finster- 
aar-horn  in  the  Alps ;  in  others,  in  perpendicular 
walls  1000  or  2000  feet  in  height,  like  some  por- 
tions of  f  Mont  Cervin  in  the  same  range ;  or  like 
natural  castles,  as  in  Mount  Athos,  in  Greece  ; 
or  in  gigantic  dome-shaped  masses,  like  Chim- 
borazo  in  the  Andes.  One  very  striking  feature 
in  elevated  mountain  ranges  consists  of  the  vast 
surface  of  snow  which  everywhere  meets  the  eye, 
particularly  in  such  mighty  mountain  ranges  as 
the  Himalaya  and  Andes.  Mountain  ranges  are 
usually  furrowed  by  deep  valleys ;  and  in  some 
parts  these  valleys  are  filled  with  vast  accumu- 
lations of  ice  and  snow,  called  glaciers,  which 
often  assume  the  most  fantastic  forms,  or  spread 
forth  like  lakes  or  seas  of  ice,  sometimes  having 
a  thickness  of  nearly  600  feet.J 

Mountain  branches,  or  ridges,  usually  of  in- 
ferior elevation,  frequently  diverge  or  branch  off 
from    the    central    line    of    a   mountain    range, 


*  In  the  Bernese  Alps.  t  In  the  Pennine  Alps. 

X  For  an  admirable  description  of  the  glaciers  of  the  Old 
World,  the  reader  is  referred  to  Rollo  in  Switzerland,  a  book 
which  may  be  perused  with  equal  profit  by  young  and  old. 


24  VARIATIONS    OF    THE    SURFACE. 

sometimes  running  almost  parallel  with  the 
principal  ridge,  like  the  Jura  *  range,  which 
branches  off  from  the  central  line  of  the  Alps  ; 
or  else  diverging  from  it  nearly  at  right  angles, 
like  the  Apennines,  from  the  same  grand  moun- 
tain range.  These  are  termed  lateral  or  side 
branches,  and  sometimes  transverse  branches. 
From  these  lateral  branches,  smaller  branches  or 
spurs  again  extend,  constituting  hills,  and  the 
latter  usually  diminish  in  height  until  they  are 
lost  in  the  plains. 

Detached  or  isolated  mountains  are  usually  of 
volcanic  origin.  In  many  instances  they  contain 
active  volcanoes,  and  they  sometimes  attain  a 
great  elevation.  Thus  Mount  Etna  in  Sicily 
has  the  altitude  of  10,8^0  feet  above  the  level  of 
the  sea,  the  peak  of  Teneriffe  in  the  Canary 
Islands  that  of  12,200,  and  Mount  Ararat  that  of 
17,2(52  feet. 

The  loftiest  summits  are  usually  met  with  in 
extensive  mountain  ranges  :  thus,  the  most  ele- 
vated summits  in  Great  Britain  occur  in  the 
mountain  ranges  of  Scotland ;  those  of  Europe, 
among  the  Alps ;  those  of  Asia  in  the  Himalaya 
Mountains;  and  those  of  America  in  the  Andes : 
as  may  be  observed  by  a  reference  to  the  follow- 

*  Between  Neufchatel  and  Lake  Geneva., 


l 


/  / 


MOUNTAINS.  25 

ing  table  of  the  height  in  feet  above  the  level  of 
the  sea,  of  the  most  remarkable  mountains  on 
the  earth's  surface. 

EUROPE. 

v/                                             j  Feet. 

"Mont  Blanc,  Alps 15,750 

Monte  Rosa,  Alps 15,150 

Mulahacen,  Sierra  Nevada,  Spain         ....  11,650 

Pic  Nethou,  Pyrenees 11,168 

Mont  Perdu,     ditto 10,950 

Etna,  volcano,  Sicily 10,880 

Argentaro,  Balkan 10,000 

Corno,  Apennines 9,250 

Skagesloestinden,  Norway        .                  ...  8,100 

Lomnitz,  Carpathians 8,750 

Parnassus,  Greece 8,000 

Schneehatten,  Norway 7,549 

Mont  d'Or,  Auvergne 6,220 

Helca,  volcano,  Iceland 5,210 

Vesuvius,  volcano,  Italy         .         .                ...  3,90  J 

BRITISH  ISLES.  / 

Ben  Nevis,  Inverness-shire 4,368 

Snowdon,  Caernarvonshire 3,571 

McGillycuddy's  Reeks,  co.  Kerry            ....  3,410 

Hehellyn,  Cumberland 3,055 

,  Kind 'Tscout,  highest  point  of  the  Peak  of  Derbyshire      .  1,981 

Beaehj  Head,  Sussex 564 


*T 


ASIA. 


Kunchin-ginga,  Himalaya 28,174 

-Dhawula-giri,         ditto     (about)         ....       28,000 
Juwahir,  ditto 25,770 


26  VARIATIOxNS    OF    THE    SURFACE 

Feet. 

Elburz,  Caucasus           ...                 .  18,400 

Ararat,  or  Agri-dagh,  Armenia         ....  17,262 

Hermon,  Syria 10,000 

Sinai,  Arabia         ...                 ....  9,300 

AFRICA. 

Kilmand-Jaro,  Zanguebar 20,000 

Abba  Yared,  Abyssinia 15,000 

Cameroons,  Biafra 13,000 

Peak,  Teneriffe,  volcano 12,200 

Spitz  Kopf,  Cape  of  Good  Hope       ....  10,000 

Table  Mount,  ditto 3,500 

NORTH  AMERICA. 

S\   Mount  St.  Elias,  volcano 17,860 

Popocatepetl,  Mexico,  ditto  .        .        .        ■        .17,716 

Fremont's  Peak,  Rocky  Mountains           .         .        .  13,560 

Black  Mountain,  Alleghanies,  N.  Carolina  .         .         .  6,476 

Mount  Washington,  White  Mountains,  N.  H.  .         .  6,285 

SOUTH  AMERICA. 

Lirima,  Andes 24,000  to  25,000 

Aconcagua,  Andes 23,907 

-£? Bahama,  ditto .  22,350 

Chimborazo,  ditto          .         .        .         .        .         «  21,415 

Sorata,  ditto     '.  *  21,286 

Illimani,  ditto 21,145 

Roraima,  Guiana 7,450 

ltambe,  Brazil 5,960 

4*J-  Cape  Horn,  Tierra  del  Fuego 1,860 

*  According  to  Johnston  and  Petermann. 


TABLE-LANDS.  27 

^  OCEANICA. 

Mowna  Roa,  Hawaii,  volcano 16,000 

Erebus,  South  Victoria  Land,  volcano       .        .         .  12,400 

Peak,  Tahiti        .                         10  875 

Egraont,  New  Zealand      ......  9,000 

Sea- View  Hill,  Australia 6,500 


El, 


Elevated  plains  or  highlands,  called  plateaus  or 
table-lands,  occur  in  various  parts  of  the  earth's 
surface.  They  sometimes  rise  abruptly  and 
almost  perpendicularly  from  the  lower  plains, 
and  it  is  in  consequence  of  this  table-like  form 
that  the  appellation  of  table-land  has  been 
adopted,  though  the  term  is  applied  to  any 
plains  of  considerable  elevation  above  the  level 
of  the  sea,  even  though  they  bear  no  resem- 
blance to  the  table-like  form ;  some  table-lands 
or  plateaus  being,  on  the  contrary,  situated  be- 
tween parallel  mountain  ranges,  the  mountains 
which  support  them  often  towering  to  great 
heights  above  these  elevated  plains. 

The  most  considerable  plateau  or  table-land 
of  Europe  occurs  in  Central  Spain,  which  has  a 
general  elevation  of  2000  feet  above  the  sea  level. 
The  plateau  or  table-land  of  Mexico  has  an  ele- 
vation of  about  7000  feet  above  the  sea.  The 
table-land  of  Quito,  wThich  is  situated  between 
two  parallel  ridges  of  the  Andes,  has  an  eleva- 
tion of  9000  feet  above  the  sea,  whilst  around  it 


28  VARIATIONS    OF    THE    SURFACE. 

rises  a  vast  assemblage  of  elevated  summits,  no 
less  than  eleven  snow-capped  mountains  being 
visible  from  that  plain.  The  most  remarkable 
table-land  on  the  surface  of  the  globe  occupies  a 
large  space  of  Central  Asia,  including  the  desert 
tracts  of  Cobi  and  Shamo  and  the  elevated 
region  of  Tibet,  the  latter  of  which  has  an 
elevation  of  15,000  feet  above  the  level  of  the 
sea. 

Plains  or  lowlands  of  greater  or  less  extent, 
presenting  comparatively  small  undulations  on 
their  surface,  and  rising  in  no  part  to  any  great 
elevation,  are  met  with  in  most  parts  of  the 
globe.  A  large  plain  or  lowland  occupies  a  con- 
siderable space  in  Europe,  commencing  on  the 
borders  of  the  North  Sea,  in  the  low  dis- 
tricts of  the  Netherlands,  and  extending  through 
Prussia  and  Poland  into  Russia,  to  the  base  of 
the  Ural  Mountains,  and  forming  in  the  latter 
country  an  almost  uninterrupted  plain  from  the 
shores  of  the  Frozen  Ocean  to  those  of  the  Black 
and  Caspian  Seas.  In  this  vast  expanse  the  sur- 
face is  scarcely  broken  by  any  eminence  except 
the  low  range  of  the  Valdai  hills,  between  Mos- 
cow and  Toropetz,  which  in  no  part  exceeds  the 
height  of  1200  feet  above  the  level  of  the  sea. 
This  extensive  plain  is  divided  by  the  Uralian 
Mountains  from  one  of  yet  larger  extent,  which 


PLAINS.  29 

forms  the  great  lowland  of  Northern  Asia.  The 
Russian  Steppes  (according  to  Koch)  are  open 
woodless  tracts,  covered  with  tall  herbaceous 
plants. 

One  of  the  most,  remarkable  lowlands  on  the 
earth's  surface  consists  of  the  vast  tract  of  barren 
sand  which  occupies  the  large  portion  of  North- 
ern Africa,  called  the  Sahara  or  Great  Desert,  and 
which  extends  from  the  borders  of  the  Atlantic 
Ocean  to  the  valley  of  the  Nile,  its  length  being 
about  2470  miles,  and  its  breadth  about  900  miles. 
It  consists  chiefly  of  low  rocky  hills,  and  an  almost 
boundless  extent  of  moving  sand,  unrefreshed  by 
a  drop  of  rain,  and  parched  and  pulverized  by 
the  intense  heat  of  a  tropical  sun.  In  some  few 
spots,  where  springs  of  water  rise  to  the  surface, 
and  admit  of  the  growth  of  vegetation,  a  verdant 
oasis  or  wady,  of  greater  or  less  extent,  varies 
the  otherwise  arid  and  dreary  surface  of  this 
enormous  desert,  appearing  like  an  island  in  the 
midst  of  an  ocean  of  sand. 

America  contains  some  lowlands  of  vast  ex- 
tent. Wide-spreading  savannahs,  or  plains,  oc- 
cupy a  large  tract  of  country,  forming  the  basin, 
or  valley,  of  the  river  Mississippi,  situated  to  the 
west  of  the  Alleghany  Mountains.  A  consider- 
able portion  of  this  great  lowland  is  remarkably 
level,  and   subject  to  annnal  inundations  from 


30  VARIATIONS    OF    THE    SURFACE. 

the  mighty  stream  by  which  it  is  traversed. 
Other  parts  consist  of  dense  forests  alternating 
with  prairies,  or  extensive  natural  meadows, 
abounding  in  wild  animals. 

In  South  America  three  remarkable  plains  or 
lowlands  occur.  The  basin  of  the  river  Oronoco 
forms  the  most  northern ;  these  plains  are  usually 
called  llanos;  the  second  great  plain  is  that 
which  is  traversed  by  the  mighty  river  Ama- 
zon, and  which  extends  from  the  shores  of  the 
Atlantic  to  the  base  of  the  Andes,  having  a 
gradual  slope,  and  being  in  many  parts  covered 
with  almost  impenetrable  forests,  and  in  others 
with  luxuriant  herbage.  These  plains  are  dis- 
tinguished as  selvas.  The  third  great  low- 
land of  South  America,  which  includes  the 
vast  plains  of  Buenos  Ayres,  and  extends  to  the 
cheerless  wastes  of  Patagonia,  forms  the  basin 
of  the  rivers  Paraguay  and  La  Plata.  These 
plains  are  usually  termed  pampas. 

Valleys  are  of  three  kinds :  —  Principal  val- 
leys ;  lateral  or  tranverse  valleys;  and  subordi- 
nate valleys. 

Principal  valleys  are  usually  valleys  of  large 
•dimensions,  enclosed  between  extensive  parallel 
ranges  of  mountains.  To  this  class  belongs  the 
Valais,  or  Valley  of  the  Rhone.  This  valley  is  bor- 
dered on  the  south  by  the  Pennine  Alps,  among 


VALLEYS.  31 

which  we  meet  with  Mont  Blanc  and  some  of 
the  other  most  elevated  mountain  peaks  in 
Europe ;  and  on  the  north  it  is  bordered  by  the 
Jura  and  the  Swiss  Alps. 

Lateral  valleys,  or  transverse  valleys,  are  so 
termed,  because  they  are  situated  among  and 
formed  by  the  lateral  or  transverse  branches  of 
mountain  ranges,  and  their  size  and  general 
arrangement  therefore  depend  on  the  magnitude 
and  direction  of  the  mountains  among  which 
they  occur. 

Subordinate  valleys,  as  the  name  implies,  are 
valleys  of  subordinate  or  smaller  size,  which  are 
formed  by  the  spurs  or  minor  branches  of 
mountain  ranges,  or  which  are  situated  among 
hills. 

Some  valleys  are  basin-shaped,  or  of  a  circular 
form,  being  surrounded  by  a  girdle  of  mountains, 
with  the  exception  of  one  small  outlet,  which 
allows  of  the  escape  of  the  superabundant 
waters.  Such  valleys  appear  to  have  formed 
the  beds  of  lakes  at  some  previous  period,  the 
waters  of  which  having  been  drained  "off  through 
the  small  gorge  or  outlet,  the  lake  has  been  con- 
verted into  a  fertile  valley.  The  beautiful  valley 
of  Cashmere  presents  an  example  of  a  basin- 
shaped  valley. 

When   valleys    are    narrow   and    difficult    of 


32  VARIATIONS    OF    THE    SURFACE. 

access,  they  are  termed  ravines,  glens,  dells,  de- 
files, gorges,  gullies,  passes  or  ports.  Narrow 
valleys  of  this  description  are  of  frequent  occur- 
rence among  steep  mountains,  and  often  present 
scenes  of  great  beauty  and  grandeur.  They 
usually  form  the  routes  by  which  mountain 
ranges  are  crossed,  and  hence  they  are  called 
ports  in  the  Pyrenees,  and  passes  in  the  Alps  and 
various  other  mountain  ranges.  As  they  are  not 
situated  at  the  highest  point,  but  just  below  the 
head  or  summit  of  the  mountain,  they  are  called 
cols  or  necks  in  the  Alps  of  Europe.  They  frer 
quently  form  the  beds  of  rivers  which  take  their 
rise  amid  the  snows  of  mountain  regions. 

The  valleys  and  plains  to  which  our  attention 
has  hitherto  been  directed,  though  low  in  eleva- 
tion as  compared  with  hills  and  mountains,  are 
all  more  or  less  above  the  level  of  the  sea,  which 
latter  forms  the  standard  by  which  all  the  undu- 
lations on  the  earth's  surface  are  measured.  In 
Central  Asia  a  large  tract  of  country  exists  which 
is  commonly  supposed  to  be  depressed  below  the 
sea  Level,  though  the  fact  is  denied  by  high 
authority.  This  extensive  area  includes  the 
Caspian  Sea  and  the  Sea  or  Lake  of  Aral 


>< 


33 


VI.  GEOLOGY. 


Geology  consists  of  an  inquiry  into  the  na- 
ture and  arrangement  of  the  various  rocks  and 
other  substances  at  or  near  the  surface  of  the 
earth. 

The  portion  of  the  earth  which  is  accessible  to 
man's  observation  is  termed  the  earth?  crust, 
though  this  forms  but  a  very  small  part  of  the 
whole  globe,  for  the  deepest  mine  hitherto  ex- 
plored scarcely  penetrates  more  than  half  a  mile 
into  the  interior  of  the  earth,  and  the  inequalities 
on  its  surface  arising  from  mountains  and  val- 
leys have  been  well  likened  to  the  roughness  on 
the  rind  of  an  orange,  as  compared  with  the 
general  mass. 

An  examination  of  the  earth's  crust  shows  us 
that  it  is  formed  of  numerous  beds  or  strata  of 
rocks,  some  of  limestone,  some  of  sandstone,  some 
of  clay ;  some  very  hard,  others  so"ft*iir?d  crum- 
bling and  readily  worn  away  by  the  action  of 
running  streams  or  the  waves  of  the  ocean. 
The  greater  number  of  these  beds  contain  organic 
remains,  that  is,  the  remains  of  animals  and 
plants,  which  are  termed  fossils.  Among  these 
the  most  numerous  are  the  remains  of  marine 
3 


34  GEOLOGY. 

animals ;  in  some  instances,  shells  and  corals 
occur  in  such  abundance  as  to  form  the  principal 
part  of  extensive  beds.  Every  part  of  the  earth 
exhibits  similar  or  nearly  similar  formations ; 
and  not  only  are  marine  fossils  met  with  in  the 
interior  of  continents  and  at  great  elevations 
above  the  sea,  but  a  vast  variety  of  plants,  corals, 
shells,  fish,  reptiles,  &c.  &c,  are  met  with  in  a 
fossil  state,  of  species  dissimilar  to  any  at  pres- 
ent on  the  land  or  in  the  waters. 

Besides  rocks,  we  meet  with  earthy  formations 
on  the  earth's  surface.  These  include  such  loose 
materials  as  are  disintegrated  or  worn  away  from 
rocks,  and  form,  when  combined  with  decayed 
animal  and  vegetable  matter,  or  humus,  the  soil 
of  meadow  and  arable  lands,  and,  generally 
speaking,  all  beds  which  are  not  consolidated,  or 
hardened.  Water-worn  pebbles,  that  is,  frag- 
ments of  rocks  rounded  by  friction  and  the 
action  of  water,  are  of  frequent  occurrence,  form- 
ing gravel  in  the  beds  of  rivers,  &c,  and  shingles 
on  the  sea-shore.  When  of  very  large  size,  they 
are  termed  boulders. 

When  rounded  pebbles  become  cemented  to- 
gether by  lime  or  any  other  material,  so  as  to 
form  a  solid  rock,  the  mass  is  called  conglomer- 
ate, and  sometimes  pudding-stone.     When  angu- 


EARTHS.  35 

lar  fragments  are  thus  cemented  together,  the 
term  breccia  is  substituted. 

The  most  abundant  materials  or  earths  of 
which  rocks  are  composed  are,  1,  silica,  or  flint; 
2,  lime;  and  3,  alumina,  or  clay. 

Silica,  or  fifes,  is  very  universally  diffused  over 
the  earth's  surface.  It  is  found  almost  pure  in 
quartz,  flint,  opal,  chalcedony,  rock  crystal,  and 
in  the  flinty  sand  of  the  sea-shore.  'Water  passes 
freely  through  sand;  and,  accordingly,  sandy 
tracts  do  not  retain  water  so  as  to  promote  vege- 
tation, and  they  are  therefore  usually  barren  ;  of 
which  the  Sahara  presents  a  striking  example. 

Lime  is  also  a  very  generally  distributed  earth, 
and  is  usually  found  in  the  form  of  carbonate  of 
lime.  Under  the  several  names  of  marble,  lime- 
stone, oolite,  and  chalk,  it  constitutes  mountains, 
and  even  ranges  of  mountains. 

Alumina  is  likewise  a  very  abundant  earth, 
and  of  great  importance  to  mankind.  It  enters 
largely  into  the  clayey  or  argillaceous  earths. 
It  forms  part  of  various  kinds  of  rocks,  and 
its  special  utility  arises  from  its  property  of  not 
permitting  water  to  pass  through  its  substance 
—  a  property  which  renders  it  of  inestimable 
value,  both  for  natural  and  artificial  reservoirs 
of  water.    ^ 

The  beds  or  layers  of  rocks  which  form  the 


36  GEOLOGY. 

crust  of  the  earth  are  divided  into  stratified  and 
unstratified. 

1.  Stratified  or  sedimentary  rocks  are  such  as 
give  evidence  of  having  been  formed  by  suc- 
cessive deposits  of  sediment  in  water.  They 
are  called  stratified,  because  the  materials  of 
which  they  are  composed  appear  to  have  been 
deposited  in  successive  strata  or  layers;  they 
are  also  called  aqueous,  because  this  appears  to 
have  been  effected  by  the  agency  of  water ;  they 
include  sandstones  or  freestones,  limestones,  clays, 
&c. 

Stratified  rocks  being  formed  by  successive 
deposits  of  layers  of  sedimentary  matter  by 
means  of  water,  it  is  evident  that  these  materials 
must  be  derived  from  some  source,  and  in  many 
instances  this  may  be  traced  to  the  disintegration 
or  crumbling  away  of  older  rocks.  Thus  gneiss 
appears  to  be  formed  by  the  disintegration  of 
granite,  conglomerate  by  that  of  various  kinds  of 
rocks. 

Although  all  the  different  kinds  of  stratified 
rocks  do  not  occur  in  every  part  of  the  earth's 
crust,  they  are  found  to  form  a  regular  series, 
and  those  which  are  of  more  recent  formation 
have  never  been  met  with  under  those  which  are 
considered  as  more  ancient.  Most  of  the  stratified 
rocks  contain  fossils ;  and  since  each  group  con- 


STRATIFIED    ROCKS.  37 

tains  a  certain  number  of  fossils  peculiar  to  itself, 
it  is  by  means  of  these  organic  remains  that  the 
relative  ages  of  the  different  strata  have  been 
determined. 

But  although  the  lowest  stratified  rocks  are 
more  ancient  than  those  which  have  been  de- 
posited above  them,  the  layers  or  beds  do  not 
always  retain  a  horizontal  position.  'Were  such 
the  case,  it  could  only  be  by  means  of  deep  cut- 
tings that  we  should  arrive  at  the  older  strata ; 
we,  however,  find,  that  owing  to  some  convul- 
sions of  the  earth,  stratified  rocks,  and  in  some  in- 
stances, whole  series  of  stratified  rocks  have  been 
thrown  out  of  their  original  horizontal  position, 
and  thus  the  various  beds  crop  out  or  come 
to  the  surface,  as  in  the  accompanying  cut, 
where  we  perceive  that  no  less  than  five  differ- 
ent kinds  of  rock  come  to  the  surface. 


Not  only  is  facility  thus  afforded  us  to  become 
acquainted  with  the  nature  of  the  lower  rocks, 
but  many  of  the  most  valuable  products  of  the 
earth  are  by  this  means  rendered  more  accessible 
to  man. 


38  GEOLOGY. 

2.  Unstratified  rocks  are  such  as  appear  to  be  of 
igneous  origin ;  that  is,  to  have  been  formed  by 
the  action  of  fire  or  intense  heat ;  they  are  called 
unstratified,  because,  instead  of  having  been  de- 
posited in  successive  layers,  like  the  stratified 
rocks,  they  seem  to  have  been  formed  by  the 
fusion  or  melting  of  the  materials  of  which  they 
are  composed,  and  the  subsequent  cooling  and 
hardening  of  the  melted  matter  into  one  great 
mass.  Granite,  basalt,  lava,  &c,  belong  to  this 
class  of  rocks.  ^ 

Unstratified  rocks  may  be  divided  into  three 
classes:  —  1.  Plutonic;  2.  Trap;  3.  Volcanic. 

Plutonic  rocks  are  rocks  which  appear  to  have 
been  formed  at  a  considerable  depth  in  the  in- 
terior of  the  earth  by  the  agency  of  heat,  and  in 
consequence  of  their  having  cooled  under  the  pres- 
sure of  superincumbent,  or  over-lying  rocks,  to 
have  become  greatly  compressed  and  hardened. 
The  principal  rock  of  this  class  is  granite,  which 
is  a  very  universally  diffused  rock,  though  in 
very  many  parts  of  the  earth  it  is  concealed  from 
our  view  by  the  stratified  rocks  which  rest  upon 
it.  In  some  parts,  granite  veins  or  branches  ex- 
tend upwards  into  the  stratified  rocks.  Granite 
occurs  in  all  of  the  New  England  States,  but  the 
purest  and  most  easily  wrought  is  found  at 
Quincy  and  Rockport  in  Massachusetts. 


UNSTRATIF1ED    ROCKS.  39 

Trap  rocks  are  formations  which  are  consider- 
ed to  be  the  products  of  volcanoes  which  have 
been  long  extinct  These  rocks,  like  the  Plutonic, 
are  supposed  to  have  been  in  a  state  of  fusion, 
but  to  have  cooled  down  under  the  pressure  of 
deep  water,  probably  of  a  profound  ocean.  Basalt 
is  one  of  the  most  abundant  rocks  of  this  class. 
It  sometimes  occurs  in  tabular  masses,  but  more 
frequently  in  regular  columns,  usually  called 
basaltic  columns.  The  Giant's  Causeway,  in  the 
north  of  Ireland,  presents  a  remarkable  instance 
of  a  formation  of  this  kind.  Trap  dikes  are 
masses  of  trap  which  have  forced  their  way  into 
or  through  other  rocks,  and  are  sometimes  of 
great  extent. 

Volcanic  rocks  are  less  compact  and  less  hard- 
ened than  either  plutonic  or  trap  rocks,  which  is 
supposed  to  be  owing  to  their  having  cooled  in 
the  open  air.  The  principal  volcanic  rocks  are, 
tufa  or  cole  tuff,  pumice-stone,  and  obsidian. 
Loose  sand,  scorice  or  cinders,  and  ashes,  are  also 
ejected  from  the  craters  or  mouths  of  volcanoes, 
and  some  volcanoes  pour  forth  streams  of  muddy 
water,  whilst  all  emit  volumes  of  gaseous  matter 
and  steam.  V^ 

The  regionsTwhere  volcanic  action  is  at  present 
displayed  in  the  greatest  energy  include  Mount 
Vesuvius  and  Mount  Etna,  and  the  adjacent  seas; 


40 


GEOLOGY. 


the  islands  of  the  Indian  Archipelago ;  Central 
America  and  the  Andes ;  some  of  the  islands  of 
Oceanica;  Iceland  and  Kamtschatka,  in  the  cold 
regions  of  the  north ;  and  South  Victoria  Land, 
amid  the  perpetual  snows  of  the  southern  polar 
regions. 

Terrific  as  are  the  effects  sometimes  produced 
by  volcanic  eruptions,  there  seems  reason  to  con- 
clude that  in  many  instances  they  may  rescue 
the  districts  where  they  occur  from  the  yet  more 
destructive  visitations  of  earthquakes.  For  it 
appears  that  the  melted  matter  in  the  interior  of 
the  earth,  being  enlarged  in  its  volume  by  the 
action  of  internal  heat,  strives  to  force  its  way 
through  the  rocks  which  form  the  earth's  crust ; 
but  on  encountering  the  outlet  afforded  it  by  the 
crater  of  a  volcano,  this  melted  matter  pours 
forth  on  the  surface  of  the  ground.  The  melted 
matter  or  lava  ejected  by  the  volcano  of  Skaptar 
Yokul,  in  Iceland,  in  the  year  1783,  was  of  im- 
mense volume.  Two  streams  of  lava  flowed  in 
opposite  directions,  the  width  of  one  stream 
being  about  twelve  or  fifteen  miles,  its  depth 
about  one  hundred  feet,  and  it  extended  to  about 
fifty  miles  from  the  mouth  of  the  volcano.  The 
second  stream  was  of  equal  depth,  but  not  of  so 
o^reat  width,  nor  did  it  extend  beyond  forty  miles. 
Had  this  mighty  mass  of  melted  matter  not  found 


EARTHQUAKES.  41 

a  vent,  we  may  well  suppose  that  it  might  have 
shattered  the  rocks  to  atoms,  and  given  rise  to 
the  most  fearful  earthquakes.  And  in  fact  it  fre- 
quently happens,  that  in  volcanic  regions,  earth- 
quakes cease  at  the  very  moment  that  eruptions 
commence  from  adjacent  volcanoes,  and  occasion- 
ally even  from  volcanoes  comparatively  remote 
from  the  convulsion.  It  thus  appears  that  in 
certain  portions  of  the  earth's  crust,  underground 
communication  must  extend  to  considerable  dis- 
tances. This  is  strikingly  displayed  in  the 
Andes,  and  a  wide  extent  of  country  at  their 
base. 

The  effects  produced  by  earthquakes  are  some- 
times very  remarkable,  convulsions  of  this  kind 
occasionally  agitating  immense  tracts  of  country, 
shattering  and  displacing  rocks,  and  even  perma- 
nently raising  continuous  tracts  of  land  above 
their  former  level,  or  causing  the  depression  of 
others ;  thus  effecting  great  alterations  in  the  sur- 
face of  the  countries  where  they  occur. 

Earthquakes  of  great  severity  sometimes  occur 
in  regions  remote  from  any  active  volcano ;  of 
this  the  tremendous  convulsion  which  took  place 
at  Lisbon  in  the  year  1755  forms  an  instance. 
On  that  occasion  the  agitation  of  the  earth's 
crust  extended  to  the  British  Isles,  and  even  to 
the  West  Indies  and  some  parts  of  North  Ameri- 


42 


GEOLOGY. 


ca.  Slight  tremors  of  the  earth  are  occasionally 
felt  in  all  parts  of  the  globe. 
"jC^Extinct  volcanoes  occur  in  various  parts  of 
the  earth's  surface ;  and  in  such  cases  we  may 
infer,  that  though  at  some  former  period  earth- 
quakes and  volcanic  eruptions  may  have  taken 
place  in  those  localities,  these  have  now  ceased, 
and  the  melted  mass  has  cooled  down  and 
formed  a  solid  rock. 

Igneous  rocks  have  in  many  cases  forced  their 
way  up  through  stratified  rocks,  forming  what 
are  termed  intrusive  rocks,  because  they  have  in- 
truded into  the  region  of  rocks  of  another  class. 
These  igneous  formations,  whilst  still  in  a  molten 
state  and  intensely  hot,  coming  in  contact  with 
the  aqueous  or  stratified  rocks,  have  usually 
changed  the  character  of  those  portions  immedi- 
ately near  them,  thus  forming  what  are  called 
metamorphic  or  transformed  rocks.  By  such 
means  limestone  rocks  have  become  transformed 
into  crystalline  marble. 

The  effects  produced  at  remote  periods  by 
violent  convulsions  of  the  earth  may  also  be 
traced  by  the  dislocations  or  faults  to  which  they 
have  given  rise.  A  dislocation  or  fault  is  so 
named  because  any  bed  or  stratum  of  rock 
where  it  occurs  has  been  rent  asunder  and  dislo- 
cated or  displaced,  so  that  one  portion  is  either 


METALLIC    VEINS.  43 

raised  above  or  depressed  below  its  former  level : 
the  stratum  being  therefore  no  longer  entire  and 
continuous,  an  interruption  ox  fault  takes  place. 

As  sandstone  and  limestone  rocks  permit 
water  to  percolate  or  pass  through  their  substance, 
which  clay  does  not,  these  dislocations  or  faults 
are  of  great  importance  in  the  natural  world,  the 
clay  strata  frequently,  in  consequence  of  their 
altered  position,  arresting  the  water  and  causing 
it,  instead  of  remaining  concealed  beneath  the 
surface  in  an  extended  sheet,  to  gush  out  in  the 
form  of  a  spring  at  the  point  where  the  disloca- 
tion has  occurred.  The  fissures  or  crevices  where 
these  displacements  have  taken  place  are  not 
unfrequently  found  filled  with  clay  and  other 
materials,  which  arrest  the  water  in  its  progress. 
y^  In  some  localities  fissures  are  found  to  con- 
tain metallic  substances,  and  are  then  distinguish- 
ed as  metallic  veins.  Such  fissures  are  frequent- 
ly found  partially  filled  with  calcareous  spar  or 
crystallized  carbonate  of  lime,  which  forms  the 
matrix  or  covering'  in  which  the  metals  are  in- 
closed. 

Metallic  or  metalliferous  veins  are  supposed  to 
have  been  partly  filled  by  mechanical  means,  that 
is,  by  particles  of  metallic  substances  being  con- 
veyed into  them  by  the  action  of  water  or  some 
other  power ;  and  partly  by  chemical  action,  that 


44  GEOLOGY. 

is,  by  sublimation,  or  fumes  rising  from  below, 
causing  deposits  to  take  place  in  these  fissures. 
The  rich  lodes  or  metalliferous  veins  of  Corn- 
wall in  England  occur  in  fissures,  more  than  one 
dislocation  having  in  many  instances  apparently 
taken  place. 

Some  metallic  deposits  appear  to  occur  in  situ- 
ations where  igneous  rocks  have  intruded  them- 
selves into  stratified  rocks,  and  converted  them 
into  crystalline  rocks.  Gold  is  supposed  to  be 
found  almost  invariably  under  such  circum- 
stances. Such  appears  to  be  the  case  in  the  rich 
deposits  near  the  Ural  mountains  in  Asiatic  Rus- 
sia ;  as  also  in  California  and  in  Australia ;  in 
all  which  places  it  is  met  with  in  quartz.  It  is  in 
pebbles  and  sand  of  the  same  rock  that  it  occurs 
in  the  beds  of  rivers,  and  in  some  cases  is  found 
spread  over  a  large  extent  of  country. 

Copper,  though  frequently  met  with  in  veins, 
is  also  found  in  extensive  masses  or  beds,  inter- 
posed between  layers  of  rock.  The  same  re- 
mark applies  to  tin,  lead,  and  silver.  Iron  is  a 
very  generally  diffused  metal,  and  is  met  with  in 
beds,  and  also  in  nodules,  or  rounded  masses, 
which  occur  in  great  abundance  among  some 
kinds  of  rocks.  \y 


J( 


45 


Vn.   THE  WATERS  OF  THE  GLOBE. 


The  waters  of  the  globe  may  be  considered 
under  four  heads; — 1.  Springs;  2.  Rivers;  3. 
Lakes;  4.  The  Ocean. 

Springs,  or  natural  fountains  of  water,  take 
their  rise  from  reservoirs,  or  sheets  of  water, 
stored  beneath  the  surface  of  the  ground.  A 
sheet  or  body  of  water  has  a  tendency  to  main- 
tain the  same  level  surface,  or  to  rise  to  the 
same  height,  wherever  it  may  spread  ;  the  height 
to  which  a  spring  will  rise  depends  therefore  on 
that  of  the  surface  of  the  reservoir  of  water  from 
which  it  is  supplied.  If  the  internal  reservoir  of 
water  be  situated  in  a  hill,  and  the  spring  should 
gush  out  in  a  valley,  the  water  may  rise  to  a  con- 
siderable height  above  the  surface  of  the  ground, 
and  form  a  natural  fountain ;  but,  on  the  other 
hand,  if  the  reservoir  be  situated  at  some  depth 
below  the  surface  of  the  ground,  the  water 
may  never  reach  the  surface,  and  the  aid  of 
a  bucket  or  a  pump  may  be  required  to  obtain 
water  from  such  a  source. 

These  internal  reservoirs  of  water  are  in  great 
measure  supplied  by  moisture  derived  from  rain, 
snow,  mist,  and  dew.  This  atmospheric  water 
enters  the   earth  through   porous   rocks,  or  by 


46  THE    WATERS    OF    THE    GLOBE. 

means  of  fissures,  and  continues  to  sink  until 
arrested  in  its  progress  into  the  interior  of  the 
earth  by  rocks  such  as  clay,  which  will  not  per- 
mit water  to  pass,  or  else  by  faults,  which  check 
it  from  spreading  into  a  wider  sheet.  The  water 
then  will  gush  forth  as  a  spring  of  greater  or  less 
size,  according  to  the  supplies  it  may  have  re- 
ceived. The  peaks  or  pointed  summits  of  moun- 
tains, owing  to  the  small  surface  they  present  for 
collecting  the  rain,  snow,  or  dew,  are  not  favor- 
able for  the  formation  of  copious  springs. 

All  springs  contain  a  certain  proportion  of  air 
and  gas,  and  also  some  solid  matter,  usually  in 
the  form  of  salts.  When  this  does  not  exceed  a 
three-thousandth  part  of  the  whole,  they  are 
termed  soft ;  but  if  the  solid  contents  exceed  this 
proportion,  the  water  becomes  hard.  "When 
these  salts  are  in  great  abundance,  the  water 
becomes  wholly  unfit  for  domestic  use,  and 
mineral  springs  are  formed.  Such  springs  are 
found  in  Worcestershire  in  England,  and  in  Amer- 
ica, throughout  the  states  of  Ohio,  Kentucky,  and 
New  York.  The  springs  in  Onondaga  county, 
N.  Y.,  are  the  most  valuable,  and  have  long  been 
worked. 

Medicinal  springs  contain  in  addition  to  com- 
mon salt,  sulphate  of  soda  and  sulphate  of  mag- 
nesia, commonly  known  as  Glauber's  and  Epsom 


THE    WATERS    OF    THE    GLOBE.  47 

salts.  The  Cheltenham  springs  in  England  are 
an  example  of  these. 

Mineral  springs  may  be  divided  into  six 
classes:  1.  Addition? ;  2.  Chalybeate;  3.  Sulphu- 
reous; 4.  Saline;  5.  Calcareous;  6.  Siliceous. 

Acidulous  waters  present  a  sparkling  appear- 
ance, which  arises  from  their  containing  carbonic 
acid  gas.  Of  this,  the  pleasant  beverage  called 
Seltzer  water  forms  an  example.  Carbonic  acid 
gas  has  the  property  of  rendering  soluble  in 
water  the  oxide  of  iron  and  various  other  min- 
eral substances,  and  therefore  these  springs 
usually  contain  some  earthy  or  saline  ingredi- 
ents. The  springs  at  Saratoga  belong  to  this 
class. 

Chalybeate  springs,  properly  so  called,  are  such 
as  hold  in  solution  either  the  carbonate  or  sul- 
phate of  iron.  A  small  spring  of  this  description 
occurs  near  Brighton  in  England. 

Sulphureous  springs  contain  sulphur  either  in 
the  form  of  sulphuretted  hydrogen,  as  the  springs 
of  Avon,  N.  Y.,  or  the  numerous  sulphur  springs 
of  Virginia ;  or  in  that  of  sulphate  of  lime,  like 
the  springs  of  Baden,  near  Vienna. 

Saline  springs  are  of  two  kinds,  brine  springs 
and  mcdiriniil  salt  springs.  Brine  springs  con- 
tain, besides  some  other  mineral  ingredients,  a 
greater  or  less  proportion  of  chloride  of  sodium,  or 


48  SPRINGS. 

common  salt,  some  springs  yielding  one-fourth  of 
their  weight  in  salt.   /\^ 

Calcareous  springs,  or  springs  highly  charged 
with  calcareous  matter,  are  met  with  in  limestone 
rocks,  from  which  they  derive  their  calcareous 
ingredients.  Water  has  the  property  of  dissolv- 
ing the  calcareous  rocks  over  which  it  flows  or 
through  which  it  niters,  and  of  again  depositing 
it,  so  as  to  form  as  the  water  evaporates  an  in- 
crustation and  in  process  of  time  a  solid  rock. 
The  Dropping  Well  at  Knaresborough  affords  an 
instance  of  such  a  spring.  The  water  falls  in  the 
form  of  a  shower  from  a  projecting  ledge  of  rock, 
and  if  plants,  or  shells,  or  the  bones  of  animals 
are  placed  so  as  to  allow  the  water  to  fall  on  them, 
they  become  embedded  in  the  tufa  or  travertine, 
as  it  is  called,  and  apparently  converted  into 
stone,  in  which  state  they  may  be  permanently 
preserved.  And  hence  these  springs  are  usnally 
termed  petrifying  or  mineralizing  springs. 

In  some  instances  when  water  percolates  or 
filters  through  limestone  rocks  into  cavernous 
recesses,  very  beautiful  formations  called  'stalac- 
tites and  stalagmites  are  met  with ;  the  stalactites 
being  suspended  from  the  ceiling  of  the  cavern 
like  icicles  of  stone,  and  the  stalagmites  being 
formed  by  successive  deposits  on  the  ground 
and  rising  in  all  varieties  of  form  from  the  floor. 


SPRINGS.  49 

Stalactites  and  stalagmites  in  some  caverns  meet 
and  unite,  presenting  the  appearance  of  columns 
supporting  an  edifice.  Travellers  who  have 
vis  ted  Mammoth  Cave  in  Kentucky  describe 
the  splendor  of  the  natural  halls  and  the  vast 
pillars  as  they  glitter  in  the  torch-light. 

Siliceous  springs  are  so  named  from  holding 
silica  ox  flint  in  solution.  These  springs  are  all 
hot  or  thermal,  as  well  as  mineral  springs.  The 
most  remarkable  springs  of  this  class  are  the 
Geysers  of  Iceland. 

Thermal  or  hot  springs  are  met  with  in  all 
parts  of  the  globe.  They  may  be  arranged  in 
two  classes :  1.  Those  which  owe  their  high  tem- 
perature to  the  natural  heat  of  the  earth  at  cer- 
tain depths ;  and  2.  Those  which  derive  it  from 
volcanic  action. 

It  has  been  found  that  on  penetrating  into  the 
earth  below  the  depth  of  100  feet,  an  increase  of 
temperature  takes  place,  both  in  solid  rocks  and 
in  internal  reservoirs  of  water,  the  increase  being 
at  the  rate  of  about  one  degree  of  Fahrenheit's 
thermometer  in  45  feet.  And,  accordingly, 
springs  which  have  their  sources  at  greater 
depths  possess  a  higher  temperature  than  those 
which  derive  their  supplies  nearer  the  surface. 
This  has  been  proved  by  water  obtained  from 


50  THE    WATERS    OF    THE    GLOBE. 

Artesian  wells  at  various  depths.  One  of  these 
near  Paris  is  1800  feet  deep.  The  water  as 
it  rises  to  the  surface  is  50  degrees  above  the 
freezing  point.  At  this  rate  of  increase  in  the  tem- 
perature, all  water  is  in  a  boiling  state  two  miles 
below  the  surface ;  at  a  depth  of  ten  miles,  if*  the 
temperature  increases  at  the  same  rate,  (and  we 
have  no  reason  to  think  that  it  does  not,)  metals 
are  at  a  red  heat ;  at  thirty,  all  known  substances 
must  be  in  a  state  of  fusion. 

The  hottest  springs  are  those  situated  near 
active  volcanoes.  Among  these  the  Geysers  of 
Iceland  hold  a  prominent  place,  their  temperature 
being  rather  above  the  point  of  boiling  water. 
Some  springs  connected  with  extinct  volcanoes 
have  a  very  high  temperature.  Many  of  these 
are  found  in  the  south  of  France. 

Bituminous  or  pertroleum  springs,  that  is, 
springs  charged  with  bitumen,  petroleum,  naphtha, 
asphaltum,  &c,  are  of  common  occurrence  in 
volcanic  districts,  or  in  districts  where  traces  of 
igneous  action  are  distinctly  observable. 


* 


RIVERS. 


The  sources  or  first  waters  of  rivers  are  usually 
derived  from  springs,  or   from   the   melting   of 


RIVERS.  51 

accumulations  of  snow.  They  do  not  therefore 
receive  their  largest  supplies  from  the  actual 
summits  of  mountains,  for  copious  springs  are 
rarely  met  with  in  such  situations,  nor  are  glaciers 
formed  on  the  highest  points  of  mountains,  but 
more  usually  on  the  declivities  or  slopes  of  the 
upper  mountain  valleys.  It  is  accordingly  in 
the  latter  localities  that  many  of  the  largest 
rivers  take  their  rise.  Thus  the  Rhone  has  its 
source  in  the  glaciers  of  the  Alps,  at  the  elevation 
of  10,000  feet  above  the  level  of  the  sea. 

It  not  unfrequently  happens  that  several  rivers 
take  their  rise  in  one  mountain  ridge,  some  of  the 
rivers  flowing  in  one  direction,  and  others  taking 
an  opposite  course.  This  ridge  is  termed  the 
water-shed.  The  mountainous  districts  of  West- 
moreland form  the  principal  water-shed  of  the 
north  of  England.  The  Eden  flows  in  one 
direction,  the  Tyne  and  Tees  in  another,  the 
Ouse  in  a  third,  &c.  The  chief  water-shed  in 
Europe  is  formed  by  the  Alpine  system,  and  its 
prolongation  into  Germany.  Thus  the  Rhine, 
the  Rhone,  and  the  Danube,  all  take  their  rise  in 
the  Alps,  the  first  discharging  itself  into  the  Ger- 
man Ocean,  the  second  into  the  Mediterranean, 
and  the  third  into  the  Black  Sea.  In  Eastern 
Europe  the  water-shed  is  formed  by  the  low 
ridge  of  the  Valdai  Hills,  not  more  than  1200 


52  RIVERS. 

feet  above  the  level  of  the  sea.  From  this  the 
Volga  flows,  which  pours  its  waters  into  the 
Caspian  Sea,  the  Dwina,*  which  falls  into  the 
Baltic,  and  the  Dnieper,  which  enters  the  Black 
Sea. 

Thus  the  Appalachian  Chain,  including  the 
Cumberland  and  Alleghany  Mountains  and  the 
Blue  Ridge,  is  the  chief  water-shed  of  the  eastern 
United  States.  It  sends  the  James,  the  Rap- 
pahannock, the  Santee  and  the  Savannah  to  the 
Atlantic,  the  Cumberland,  the  Monongahela, 
the  Kentucky  and  the  Tennessee  to  the  Ohio. 

The  portion  of  country  through  the  course  of 
which  a  river  lies,  and  which  is  drained  by  it 
and  its  tributary  streams,  is  called  its  basin. 
The  extent  of  the  basin  of  the  Thames  is  esti- 
mated at  about  5000  square  miles.  The  area 
drained  by  the  river  Thames  and  its  tributary 
streams  is  very  small,  compared  with  that  drained 
by  some  of  the  great  rivers  of  the  globe.  The 
largest  river  basin  in  Europe,  as  will  be  observed 
in  the  following  table,  is  that  of  the  Volga,  the 
largest  in  the  world  that  of  the  Amazon. 


*  On  many  American  maps  the  name  of  this  river  is  spelt 
Duna.  The  pupil  must  not  confound  it  with  another  river  of  the 
same  name  which  flows  into  the  White  Sea. 


RIVERS. 


53 


BIVEB.  BASINS.  SQUARE  MILES. 

Thames 5,000 

Rhine  89,000 

Danube 312,000 

Ganges 443,000 

Volga  653,000 

Mississippi 1,100,000 

Amazon 1,920,000 

The  velocity  of  a  river  depends  in  a  great 
degree  on  the  nature  of  the  country  in  which  it 
takes  its  rise,  and  which  it  traverses.  The 
Thames  has  its  source  at  an  elevation  of  only  a 
few  hundred  feet  above  the  level  of  the  sea,  and, 
since  its  whole  course  lies  through  a  comparative- 
ly level  country,  it  flows  with  a  moderate  velocity 
and  presents  no  instances  of  torrents,  rapids,  or 
waterfalls,  a  circumstance  which  renders  it  par- 
ticularly available  for  the  purposes  of  navigation ; 
and  thus  though  it  may  appear  insignificant 
when  compared  with  some  of  the  mighty  streams 
on  the  earth's  surface,  it  possesses  advantages 
superior  to  most  rivers,  having  also  an  unimpeded 
entrance,  and  being  navigable  for  large  vessels  to 
the  very  banks  of  the  metropolis. 

Rivers  which  take  their  rise  in  elevated  moun- 
tain districts  usually  flow  with  great  velocity  in 
the  earlier  part  of  their  course,  rushing  down  in 
torrents,  or  leaping  down  in  cascades  or  cataracts. 
When  waterfalls  are  of  an  impetuous  character,  i 


54  RIVERS. 

they  are  generally  termed  cataracts ;  when  more 
gentle,  they  are  called  cascades.  Waterfalls  are 
very  numerous  among  the  Alps  and  other  moun- 
tainous regions.  When  a  continued  slope  occurs 
in  the  bed  of  a  river,  rapids  are  formed. 

It  occasionally  happens  that,  owing  to  local 
peculiarities  at  the  mouths  of  rivers,  accumula- 
tions of  sedimentary  matter  take  place  in  the 
middle  of  the  stream,  dividing  it  into  two  or  more 
branches.  By  this  deposition  of  alluvium,  deltas 
are  formed,  many  of  them,  those  of  the  Ganges, 
the  Orinoco,  the  Mississippi  and  the  Rhine,  for 
example,  being  of  great  extent.  The  term  delta 
is  applied  to  these  on  account  of  their  triangular 
form,  like  the  letter  A  of  the  Greek  alphabet. 

Some  rivers  which  fall  into  the  ocean,  and 
have  estuaries  or  wide  channels  at  their  mouths, 
are  subject  to  a  great  swell  or  sudden  rise  of  the 
waters  when  the  tide  enters  the  river.  This  is 
called  the  bore.  It  occurs  especially  at  spring 
tides,  when  a  more  than  ordinarily  large  volume 
of  water  enters  the  mouth  of  the  river.  The  bore 
may  be  observed  in  the  Severn,  and  some  other 
rivers  of  Great  Britain,  and  is  displayed  on  a 
grand  scale  in  the  rivers  Ganges  and  Amazon, 
In  the  latter  river,  for  three  successive  days  at 
the  time  of  the  equinoxes,  five  waves  from  12  to 


RIVERS.  55 

15  feet  high  follow  each  other  up  the  river,  pre- 
senting a  truly  singular  spectacle. 

Most  rivers  are  subject  to  an  occasional,  and, 
in  some  instances,  periodical  increase  in  the 
volume  of  their  waters.  In  the  rivers  of  Great 
Britain  and  the  United  States,  these  flood  sea- 
sons, or  freshets,  as  they  are  termed,  are  by  no 
means  regular,  being  partly  dependent  on  the 
melting  of  the  snows,  and  partly  on  occasional 
heavy  falls  of  rain.  In  countries  where  the 
climate  is  less  variable,  these  flood  seasons  in 
the  rivers  are  usually  periodical.  Thus  the  flood 
season  in  the  Volga,  being  dependent  on  the 
melting  of  the  snows  in  Northern  Russia,  takes 
place  in  June.  The  rise  of  the  Nile  being 
dependent  on  the  periodical  rains  which  fall 
abundantly  on  the  mountains  where  its  source 
is  situated,  almost  invariably  begins  in  the  middle 
of  June,  and  the  waters  continue  to  increase 
until  the  end  of  August  or  beginning  of  Sep- 
tember, when  the  river  is  at  its  greatest  height 
and  the  whole  valley  of  Egypt  is  usually  inun- 
dated. 

The  number  of  considerable  rivers  which  pour 
their  waters  into  the  ocean  is  estimated  at  about 
440  in  the  Old  World,  and  140  in  the  New 
World. 

The  following  table  gives  the  length  and  situa- 


56 


RIVERS. 


tion,  and  also  the  termination  of  some  of  the 


principal  rivers  on  the  surface  of  the  globe. 


^C 


RIVER. 

Mississippi  and  Mis- 
souri   .    .    . 

Nile 

Amazon  .     .    . 

Yang-tse-Kiang 

Niger    

Mississippi  proper 

Volga 

La  Plata  .... 
St.  Lawrence  .  . 
Indus  .... 
Danube  .... 
Euphrates  .  .  . 
Oroaoco  .... 
Ganges  .... 
Colombia  or  Oregon 
Dnieper  .... 
Gariep  or  Orange    . 

Ural 

Ohio      .    .    .    :    . 


LOCALITY. 

United  States 


TERMINATION 

.  Gulf  of  Mexico 


Rhine 


Seine     .    . 
Connecticut 
Hudson 
Thames 


Nubia  and  Egypt    .    .  Mediterranean  Sea 

Brazil Atlantic  Ocean  . 

(  hina Pacific  Ocean 

Niiiritia Gulf  of  Guinea  . 

United  States      .    .     .  Gulf  of  Mexico  . 

Russia Caspian  Sea  .  . 

Brazil  and  La  Plata      .  Atlantic  Ocean  . 

Canada Gulf  of  St  Lawrence 

Hindostan      ....  Indian  Ocean  . 

Germany,  &c.     .    .     .  Black  Sea       .  . 
Turkey  in  Asia   .    .     .  Persian  Gulf 

Venezuela Atlantic  Ocean  . 

Hindostan      ....  Bay  of  Bengal  . 
United  States      .    .     .Pacific  Ocean 

Russia Black  Sea  .    .  . 

South  Africa  ....  Atlantic  Ocean  . 

Russia Caspian  Sea    .  . 

United  States      .     .    .  Mississippi     .  . 
Switzerland, Germany 
&  Holland     .    . 


North  Sea 


France        English  Channel 

United  States      .    .    .  Long  Island  Sound 
United  States     .    .    .  Atlantic  Ocean    . 
England North  Sea  .    .    . 


4200 

3600 
3600 
3300 
3000 
2400 
2200 
2200 
2000 
1800 
1700 
1700 
1550 
1500 
1500 
1200 
1050 
950 
950 

760 

440 
400 
350 

215 


Note.  —  This  list  of  rivers  is  changed  but  slightly  from  the  Eng- 
lish edition.  While  it  should  be  so  thoroughly  learned,  that  the 
pupil  can  give  the  locality,  termination  and  length  of  any  river 
taken  at  random  from  the  table,  still  the  teacher  should  impress 
the  fact  that  the  lengths  of  many  of  the  largest  rivers  of  the  globe 
have  never  been  obtained  with  exactness,  and  that  neither  this 
table,  nor  in  fact  any  table  in  the  present  state  of  geographical 
knowledge,  can  be  appealed  to  as  final   authority  upon  the 


LAKES.  57 

length  of  rivers.  We  find,  on  collating  various  statistics  bearing 
upon  this  point,  a  deviation  in  one  instance  of  1300  miles  from 
the  length  given  by  Miss  Zornlin.  This,  it  is  true,  is  an  extraor- 
dinary case ;  the  river  is  the  Kiang-Ku  or  Yang-tse-Kiang, 
an  immense  and  splendid  stream,  but  not  well  known. 

X 

LAKES. 

Lakes  are  of  different  kinds.  Some  may  be 
considered  as  tanks  or  reservoirs  which  receive 
the  first  outbreakings  of  a  spring ;  and  in  lakes 
of  this  description,  if  the  volume  or  quantity  of 
water  be  of  small  amount,  the  evaporation  from 
the  surface  may  be  sufficient  to  dispose  of  the 
whole  supply  from  the  spring ;  and  therefore 
such  a  lake  will  require  no  outlet.  Such  is  the 
case  with  a  large  number  of  small  lakes  and 
ponds  in  all  parts  of  the  globe.  If  the  amount 
of  water  sent  forth  by  a  spring  be  more  than  will 
fill  the  hollow  which  forms  the  basin  of  the  lake, 
the  water  will  scoop  out  for  itself  a  channel,  and 
issue  forth  either  in  the  form  of  a  little  brook,  of 
a  rivulet,  or  of  a  river.  Many  important  rivers 
have  their  sources  in  small  lakes.  Thus  the 
river  Volga  commences  its  course  by  issuing 
from  the  small  Lake  of  Ternoff,  the  Amazon  from 
Lake  Reyes,  and  the  Mississippi  from  Lake 
Itasca. 


58  LAKES. 

Other  lakes  consist  of  basins  or  reservoirs 
which  occur  in  the  line  of  a  river's  course,  into 
which  its  waters  flow,  and  which,  having  filled 
the  cavity,  issue  forth  from  some  other  point.  A 
river  may  form  numerous  lakes  of  this  kind  in 
its  progress.  Thus  the  Mississippi,  in  the  earlier 
part  of  its  course,  passes  through  no  less  than 
eight  such  lakes,  some  of  which  are  of  consider- 
able size.  Most  of  the  lakes  or  loughs  *  of  Ireland 
are  thus  formed.  Indeed,  the  Shannon  river  is 
but  a  succession  of  these. 

Some  lakes  consist  of  basins  or  cavities  into 
which  rivers  flow,  but  which  on  account  of  their 
depression  or  their  mountainous  surroundings 
have  no  outlet.  Instances  of  this  class  are  the 
Caspian  Sea  and  the  Sea  of  Aral,  which  are 
great  inland  lakes,  and  Lake  Asphaltites  or  the 
Dead  Sea.  The  rivers  which  supply  them  are 
continually  bringing  down  a  portion  of  salt  which 
they  have  dissolved  from  the  soil  through  which 
they  pass,  and  which  occasions  the  brackishness 
of  most  river  water.  As  evaporation  proceeds, 
the  purer  portions  only  are  removed,  the  saline 
matter  remains,  and  thus  salt  lakes  are  formed. 
The  Dead  Sea  receives  the  waters  of  the  Jordan 
on  the  north,  of  the  Arnon  on  the  east,  and  of 

*  Pronounced  locks,  nearly. 


LAKES.  59 

the  brook  Kedron  or  Cedron  on  the  west.  Its 
waters  are  salter  than  those  of  the  ocean,  and 
this  fact  is  accounted  for,  partly  by  the  explana- 
tion just  offered,  and  partly  by  the  circumstance 
that  it  is  constantly  dissolving  the  blocks  of  salt 
which  are  found  on  its  southern  shore. 

Lakes  are  sometimes  formed  in  the  craters  of 
extinct  volcanoes,  and  in  such  cases  the  waters 
are  usually  strongly  impregnated  with  sulphur 
and  bitumen. 

Some  lakes  are  periodic;  that  is,  subject  to 
have  their  basins  alternately  empty  and  full  of 
water.  Of  this  description  is  the  Lake  of  Zirk- 
nitz,  in  Carniola,  which  in  midsummer  is  dry 
and  allows  a  luxuriant  crop  of  grass  to  cover  its 
bottom,  but  is  filled  in  autumn,  and  continues  full 
through  the  winter  and  spring. 

The  lakes  in  the  British  Isles  are  of  small  size. 
Windermere  is  the  largest  English  lake,  not  ex- 
ceeding eleven  miles  in  length  and  one  mile 
in  width.  The  largest  European  lakes  are  the 
lakes  of  Ladoga  and  Onega  in  Russia.  The 
Caspian  Sea  may  be  considered  as  the  largest 
lake  on  the  face  of  the  globe,  its  length  being 
about  700  miles,  and  its  width  about  210  miles. 
North  America  contains  the  largest  fresh  water 
lakes  in  the  world,  and,  indeed,  a  vast  chain  of 
connected  lakes  occupies  a  wide  surface  of  coun- 


60 


THE    OCEAN. 


try  in  its  more  northerly  regions.  This  chain 
includes  Lakes  Superior,  Huron,  Michigan,  Erie, 
and  Ontario,  the  surplus  waters  of  which,  after 
having  formed  the  grand  Fall  of  Niagara  be- 
tween Lakes  Erie  and  Ontario,  are  discharged 
into  the  Atlantic  by  the  river  St.  Lawrence. 
The  frequent  and  violent  storms  to  which  large 
lakes  are  eminently  subject  are  produced  by  the 
violent  rushing  of  the  wind  down  the  sides  of 
the  mountains  by  which  they  are  surrounded. 
The  scenery  of  small  lakes  is  the  most  beautiful 
in  the  world. 


X 


THE    OCEAN. 


The  extent  of  the  vast  mass  of  waters  called 
the  Ocean  greatly  exceeds,  as  we  have  already 
seen,  that  of  the  dry  land  on  the  surface  of  the 
globe.  This  is  an  arrangement  of  great  impor- 
tance in  the  natural  world,  for  abundant  supplies 
are  thus  afforded,  by  evaporation  from  its  vast  sur- 
face, for  the  large  amount  of  moisture  required 
to  water  the  earth,  which  descends  in  the  form 
of  showers  and  dew. 

The  ocean  consists  of  one  great  fluid  mass ; 
and  in  accordance  with  the  laws  by  which  fluids 
are  governed,  its  waters  flow  into  and  occupy  the 
great  depressions  on  the  Earth's  surface  which 


THE    OCEAN.  61 

form  its  bed,  maintaining  a  general  level  in  all 
parts  of  the  globe,  whatever  may  be  the  undula- 
tions of  the  ground  on  which  it  rests. 

Although  thus  in  fact  one  mighty  whole,  the 
ocean  has  received  in  geographical  descriptions 
several  nominal  divisions  and  subdivisions. 

The  two  principal  divisions  of  the  ocean  are 
those  of  the  Atlantic  and  the  Pacific,  which  are 
formed  by  the  two  great  continents.  The  Austral 
or  Southern  Ocean  may  be  regarded  as  forming 
a  third  division,  and  occupies  that  portion  of  the 
ocean  not  included  in  the  two  former  divisions. 
Its  limits  may  be  traced  by  a  line  passing  round 
the  globe,  and  touching  the  Cape  of  Good  Hope, 
Cape  Horn,  and  the  southern  extremity  of  Tas- 
mania (Van  Diemen's  Land). 

The  Atlantic  Ocean  is  sometimes  subdivided 
into  three  portions ;  the  Northern  Ocean,  which 
includes  the  Polar  Seas,  and  extends  to  an  imag- 
inary line  drawn  across  the  ocean,  from  the 
northern  extremity  of  the  British  Isles  to  the 
souttiern  extremity  of  Greenland;  the  North 
Atlantic,  extending  from  that  line  to  the  Equa- 
tor ;  and  the  South  Atlantic  from  the  Equator  to 
the  southern  extremities  of  Africa  and  America, 
that  is,  to  the  Austral  or  Southern  Ocean. 

The  Pacific  has  also  three  subdivisions ;  the 
North  and  the  South  Pacific,  and  the  Indian  Ocean. 


62  THE    OCEAN. 

The  division  between  the  North  and  the  South 
Pacific  is  marked  by  the  line  of  the  Equator ; 
and  the  latter  extends  to  the  southern  coasts  of 
Australia.  The  Indian  Ocean  comprises  the 
seas  extending  from  Australia  and  the  western 
limits  of  the  Indian  Archipelago  to  the  eastern 
coasts  of  Africa. 

In  various  parts  of  the  great  continents,  deep 
inlets,  called  branch  or  inland  seas,  occur,  pene- 
trating far  into  the  interior,  and  communicating 
with  the  main  ocean  either  by  narrow  straits,  as 
the  Red  Sea,  the  Mediterranean,  and  the  Baltic  ; 
or  by  wider  channels,  as  the  White  Sea,  the 
Yellow  Sea,  Baffin's  Bay,  &c. 

Smaller  inlets  of  the  sea  are  of  frequent  occur- 
rence, especially  in  districts  where  mountain 
ranges  approach  the  borders  of  the  ocean. 
Such  are  the  lochs  of  Scotland,  the  voes  of  the 
Shetland  Isles,  and  the  fiords  of  the  coast  of 
Norway.  The  term  lagoon  is  usually  applied  to 
the  lake-like  inlets  on  the  shores  of  the  Adriatic 
Sea,  in  the  midst  of  one  of  which  the  city  of 
Venice  is  built. 

The  ocean  varies  greatly  in  its  depth,  but  is  sup- 
posed generally  speaking,  to  be  deepest  at  a  dis- 
tance from  land,  and  shallowest  in  channels  and 
straits  and  near  islands,  though  it  differs  much 
in  its  depth  in  the  immediate  vicinity  of  dry  land, 


THE    OCEAN.  63 

according  to  the  character  of  the  surface,  whether 
the  shores  may  be  flat  or  rise  abruptly  from  the 
sea.  The  mean  or  average  depth  of  the  sea 
round  the  comparatively  level  coasts  of  South 
Britain,  is  considered  not  to  exceed  120  feet ;  off 
those  of  Scotland,  to  be  about  360  feet ;  and  off 
the  western  coast  of  Ireland,  where  rocks  of  a 
precipitous  character  abut  upon  the  sea,  to  have 
the  depth  about  2000  feet.  In  some  parts  of  the 
mid- Atlantic  Ocean  the  plumb-line  has  been  let 
down  to  the  depth  of  27,000  feet,  without  reach- 
ing the  floor  of  the  ocean,  and  it  is  probable  that 
we  shall  never  be  able  to  ascertain  with  certainty 
the  greatest  depth,  for  no  line  can  be  made  strong 
enough  to  bear  its  own  weight,  and  yet  be 
manageable,  if  we  attempt  to  go  much  beyond 

five  miles  and  a  half  (27,000  feet). . 

The  temperature  of  the  ocean's  surface  appears 
generally  to  agree  with  that  of  the  climate  in 
which  it  is  situated,  that  is,  with  the  temperature 
of  land  at  the  level  of  the  sea.  In  warm  climates 
the  temperature  of  the  deep  sea  diminishes  with 
the  depth  below  the  surface,  until  a  certain  depth 
is  reached,  below  which  it  appears  to  retain  an 
equable  temperature,  this  being  about  40°  Fah- 
renheit. In  the  Polar  Seas,  where  the  tempera- 
ture at  the  surface  of  the  ocean  is  lower  than 
40°,  the  temperature  is  found  to  increase  until  it 


64  THE    OCEAN. 

reaches  that  point.  About  N.  lat.  70°  the  tem- 
perature of  the  ocean  is  considered  to  be  the 
same  at  all  depths. 

The  waters  of  the  ocean  are  salt,  holding  in 
solution  various  saline  matters  which  impart  to 
to  them  a  disagreeable  taste,  and  render  them 
unfit  for  the  beverage  of  man.  The  saline  in- 
gredients amount  to  rather  more  than  thirty-five 
grains  in  a  thousand  grains  of  sea-water.  The 
most  abundant  of  these  is  chloride  of  sodium,  or 
common  salt,  which  in  general  forms  above  one- 
third  of  the  whole  saline  matter.  Besides  this, 
sea-water  contains  some  magnesia,  lime,  potash, 
and  traces  of  iodine  and  bromine.  The  specific 
gravity  or  weight  of  sea-water  is  greater  than  that 
of  pure  water.  Pure  water  (at  the  temperature 
of  60°)  is  reckoned  at  1000 ;  the  specific  gravity 
of  sea-water  is  1027.  Sea-water  in  the  vicinity  of 
land  is  usually  less  salt  than  in  the  deep  ocean  ; 
probably  owing  to  the  drainage  of  the  land  and 
the  influx  of  rivers.  For  the  same  reason,  branch 
or  inland  seas  are  ordinarily  less  salt  than  the 
ocean.  Thus,  the  waters  of  the  Baltic  Sea, 
into  which  numerous  important  rivers  pour  their 
streams,  are  much  less  salt  than  those  of  the 
ocean. 

The  Mediterranean  Sea  forms  an  exception  to 
the  general  rule  of  the  inferior  saltness  of  branch 


ICEBERGS.  65 

or  inland  seas,  the  waters  of  that  sea  being  found 
to  contain  a  larger  proportion  of  saline  matter 
than  those  of  the  Atlantic  Ocean.  This  pecu- 
liarity is  supposed  to  be  attributable  to  the  prox- 
imity of  this  branch  of  the  ocean  to  the  burning 
sands  of  Africa,  and  also  to  the  parching  winds 
which,  passing  over  this  sea  after  traversing 
those  desert  tracts,  cause  an  extraordinary 
amount  of  evaporation  to  take  place  from  its 
surface. 

The  freezing  point  of  water  is  affected  by  its 
saline  contents.  The  freezing  point  of  fresh 
water  being  32°  Fahrenheit,  that  of  sea-water  is 
28°  or  29°.  The  waters  of  the  oceau  therefore 
require  a  greater  degree  of  cold  than  do  those 
of  a  fresh  water  lake,  to  convert  them  into  a 
solid  mass  of  ice  ;  and  it  is  only  in  very  cold 
climates  that  ice  is  formed  in  the  open  sea. 

Icebergs,  or  mountains  of  ice,  though  occa- 
sionally formed  in  the  sea  itself  by  the  accumu- 
lation of  ice  and  snow,  appear  more  frequently 
to  consist  of  glaciers  which  have  been  originally 
formed  on  the  shores,  and  which,  becoming  de- 
tached and  falling  into  the  water,  have  been 
floated  out  to  sea.  Icebergs  are  met  with  in 
great  numbers  about  N.  lat.  70°,  but  they  are 
sometimes  carried  by  currents  into  much  lower 
latitudes,  having  been  observed  in  the  northern 
6 


66  THE    OCEAN. 

hemisphere  in  the  parallel  of  40%  and  in  the 
southern  hemisphere  in  that  of  36°.  Some  ice- 
bergs are  of  enormous  size,  being  two  or  three 
hundred  feet  in  height  above  the  water,  and  pro- 
bably having  about  eight  times  that  depth  below 
the  surface,  and  extending  sometimes  for  two 
miles  or  more.  These  are  found  not  so  often 
alone  as  in  groups,  and  the  surface  which  they 
expose  is  sometimes  so  great  as  perceptibly  to 
freshen  the  sea  in  their  vicinity.  ^^ 

Sea- water  when  seen  in  small  quantities  seems 
to  be  colorless,  but  when  seen  in  a  large  mass, 
its  natural  color  appears  to  be  «sky-blue.  Since 
the  water  acts  like  a  mirror  and  reflects  the  hues 
of  the  ^haraging  skies,  it  may  often  appear  to 
assume  different  tints,  as  the  sky  is  clear  or 
cloudless,  or  according  to  the  position  of  the 
sun.  Thus  at  times  it  will  appear  of  a  dull 
dead  color,  at  others  it  will  present  varied  tints 
of  purple  and  green,  at  others,  shine  like  bur- 
nished gold,  ^yf 

In  some  cases,  however,  the  general  color  of 
the  ocean  is  affected  by  the  nature  of  its  bed, 
especially  if  the  water  be  shallow ;  for  yellowish 
sand  mingling  its  color  with  the  natural  blue 
tint  of  the  ocean  imparts  a  greenish  hue  to  the 
whole  mass.  If  the  bed  of  the  sea  be  red,  as  is 
the  case  in  some  parts  of  the  Mediterranean, 


ITS    COLOR.  67 

(probably  owing  to  the  red  coral  which  abounds 
in  some  parts),  this  red  hue  combined  with  the 
bright  blue  of  the  waters  of  that  sea  gives  a  pur- 
ple tint.  When  the  water  is  very  clear,  the  red 
hue  prevails,  and  the  waters  appear  tinged  with 
that  color.  Thus,  in  the  Bay  of  Loango,  off  the 
western  coast  of  Africa,  the  water  appears  so 
red  that  it  might  be  supposed  to  be  mixed  with 
blood. 

Sometimes  color  is  imparted  to  the  ocean  by 
the  presence  of  innumerable  minute  living  crea- 
tures. Thus,  in  the  Polar  Seas,  the  water  in 
some  parts  appears  of  a  green  hue,  in  conse- 
quence of  its  being  filled  with  myriads  of  yellow 
semi-transparent  medusa.  From  a  similar  cause, 
the  ocean  in  other  parts  appears  of  a  brown 
color,  in  others  of  a  milky  white,  and  in  others 
of  a  deep  red  hue. 

The  luminosity  or  phosphorescence  of  the  ocean 
appears  in  some  instances  to  be  produced  by 
decaying  animal  and  vegetable  substances,  but 
in  others  to  arise  from  the  presence  of  vast  num- 
bers of  living  animals,  which,  like  the  glow- 
worm, have  the  power  of  emitting  light.  Some 
of  these  luminous  animals  shine  like  liquid 
silver,  and  others  sparkle  like  amethysts  and 
emeralds. 


TIDES,  WAVES,    AND    CURRENTS. 


TIDES,  WAVES,  AND  CURRENTS. 

The  waters  of  the  ocean  are  in  perpetual 
movement  from  the  effects  of  tides,  winds,  and 
currents. 

The  waters  of  the  ocean  are  retained  in  their 
bed  on  the  surface  of  the  globe  by  the  attraction 
of  gravitation,  that  is,  by  the  power  which  has 
been  imparted  to  all  particles  of  matter  to  draw 
towards  them  or  attract  other  particles  of  matter. 
This  power  of  attraction  is  great  in  proportion 
to  the  mass  of  any  body,  a  large  mass  of  matter 
having  a  much  greater  power  of  attraction  than 
a  small  one  ;  and  as  the  earth  is  of  much  greater 
mass  than  the  particles  of  water  on  its  surface,  it 
attracts  them  and  keeps  them  in  their  assigned 
place.  But  the  sun  and  moon  also  possess  this 
power  of  attraction,  and  notwithstanding  their 
distance  from  the  waters  on  the  earth's  surface, 
attract  and  draw  them  up  to  a  certain  elevation 
in  the  wide  open  ocean. 

The  vast  mass  of  the  waters  being  drawn  up 
by  the  influence  of  the  moon  into  a  great  moun- 
tain or  curve  of  water  in  the  wide  open  sea, 
forms  what  is  termed  the  great  primary  wave, 
or  tidal  wave.     When  the  waters  of  the  ocean 


TIDES.  69 

are  thus  drawn  up  to  form  this  great  wave,  they 
necessarily  recede  from  our  shores,  thus  giving 
rise  to  ebb  tide  or  low  water.  But  when  the  tem- 
porary attraction  ceases,  the  waters  having  been 
raised  above  their  ordinary  level  naturally  flow 
down  and  spread  in  all  directions,  returning  to 
our  shores,  and  forming  flood  tide  or  high  water* 
This  culmination  or  rising  of  the  waters  in 
this  great  wave  takes  place  twice  in  twenty-four 
hours  and  fifty  minutes.  The  combined  influ- 
ence of  the  sun  and  moon  at  new  and  full  moon 
augments  the  size  of  this  wave,  and  causes  the 
spring  tides  at  those  periods.  The  great  Atlan- 
tic tidal  wave  arrives  first  at  the  western  shores 
of  the  British  Isles ;  it  then  divides  into  two 
branches,  the  principal  of  which  passes  round 
the  coast  of  Scotland,  and  travels  southward 


*  An  attempt  to  popularize  the  theory  of  tides  must  lead  to 
much  misconception,  but  Miss  Zornlin's  explanation  is  so  lucid, 
so  far  as  it  extends,  that  we  have  preferred  to  retain  it,  with  the 
hope  that  it  may  induce  the  pupil  to  consult  more  elaborate  works, 
and  make  himself  master  of  this  interesting  subject.  It  will  be 
noticed  that  no  explanation  is  attempted  of  the  flood-tide  on  the 
side  of  the  earth  which  is  turned  from  the  moon.  If  the  class  is 
sufficiently  mature  to  profit  by  the  explanation,  the  teacher  can 
avail  himself  of  the  black-board  to  illustrate  that  portion  of  the 
subject.  For  a  full  and  lucid  exposition  of  the  theory  of  the 
tides,  the  editor  would  refer  to  Murray's  Encyclopaedia  of 
Geography. 


70  TIDES,    WAVES,    AND    CURRENTS. 

until  it  reaches  the  mouth  of  the  Thames,  where 
it  encounters  the  lesser  branch,  which  has  swept 
along  the  western  shores.  High  water  at  the 
various  points  along  the  coasts  is  dependent  on 
the  arrival  of  this  great  wave,  though  some  va- 
riations are  caused  by  local  peculiarities,  such  as 
the  form  of  the  coast,  &c. 

The  height  of  the  tides  varies  greatly  in  the 
different  parts  of  the  earth,  but  as  a  general  rule 
it  depends  upon  the  nature  of  the  shore.  Where 
the  waters  accumulate,  as  in  those  bays  which 
communicate  with  the  sea  by  wide  channels, 
the  tides  rise  very  high ;  as  for  example,  at 
Bristol  in  England,  where  the  rise  is  about  fifty 
feet.  Perhaps  the  most  remarkable  instance  is 
the  well-known  tide  wave  of  the  Bay  of  Fundy, 
which  in  some  seasons  of  the  year  attains  the 
height  of  seventy  feet.  At  the  shores  of  small 
islands,  on  the  contrary,  the  elevation  of  the 
wave  is  not  great.  At  St.  Helena  it  never  ex- 
ceeds three  feet,  and  at  some  of  the  islands  of 
the  Pacific  the  spring  tide  is  but  five  feet  in 
height,  the  neap  tide  not  over  two-and-a-half. 

The  waves  of  the  sea  which  are  caused  by 
the  action  of  the  wind,  and  which  are  called 
secondary  waves,  or  wind  waves,  are  of  a  totally 
different  character  from  the  tidal  wave.  There 
is  much  appearance  of  confusion  in  an  agitated 


WAVES    AND    CURRENTS.  71 

sea,  but  in  the  midst  of  this  apparent  disorder 
order  reigns,  and  it  seems  to  be  in  a  great  meas- 
ure owing  to  the  continual  slight  shifting  of  the 
wind,  that  waves  appear  so  frequently  to  cross 
and  intercept  each  other.  The  influence  of  the 
wind  is  supposed  not  to  extend  to  a  greater 
depth  than  forty  or  fifty  feet,  the  deep  sea, 
though  raised  in  a  great  mass  by  the  grand 
tidal  movement,  being  free  from  agitation. 
Wind  waves  at  a  distance  from  the  shore  are 
comparatively  long  and  low,  but  as  they  ap- 
proach the  coast  where  the  water  is  shallow, 
they  assume  a  greater  curvature,  and  fall  on 
the  beach  either  in  gentle  ripples,  or  in  mag- 
nificent breakers,  according  to  the  depth  of  the 
water  and  the  force  of  the  wind. 

The  heavy  swell  which  occasionally  takes 
place  on  the  northern  coasts  of  some  of  the 
West  Indian  Islands,  called  the  ground  sea,  is 
supposed  to  originate  in  distant  storms  of  wind 
in  the  Atlantic  Ocean.  The  sea,  although  the 
air  is  calm,  suddenly  rises  as  if  agitated  by  a 
heavy  gale,  and  wave  follows  wave  in  quick 
succession,  crested  with  foam  and  bursting  on 
the  beach  with  great  impetuosity. 

Currents*  in   the   ocean    arise   from  various 
• 
*  The  chart  of  the  currents  will  be  found  on  page  1& 


72  TIDES,    WAVES,    AND    CURRENTS. 


causes:  they  may  be  produced  by  long-con- 
tinued gales  of  wind ;  by  the  melting  of  the 
polar  ice ;  or  by  any  cause  that  may  give  rise 
to  onward  movements  of  limited  portions  of 
the  great  mass  of  waters.  Some  currents  of 
the  ocean  are  permanent :  the  most  remark- 
able of  these  are  the  polar  currents,  and  the 
equatorial  currents. 

The  polar  currents  are  produced  by  the  per- 
petual movement  of  the  waters  from  the  polar 
regions  to  the  equator.  In  accordance  with 
the  laws  of  mechanics,  an  accumulation  of 
the  waters  of  the  ocean  takes  place  in  that 
part  of  the  globe  which  has  the  greatest  veloc- 
ity of  motion :  and  as  the  earth  in  turning 
on  its  axis  moves  with  far  greater  velocity  at 
the  equator  than  it  does  in  high  latitudes,  the 
waters  consequently  flow  continually  towards 
that  line,  thus  forming  currents  in  the  ocean 
which  move  from  the  north  and  south  poles  to 
the  equator. 

This  culmination  or  accumulation  of  the 
waters  of  the  ocean  at  the  equator,  tends  to 
produce  the  equatorial  currents,  which  consist 
of  the  continuous  progression  of  the  tropical 
seas  in  a  westerly  direction.  When  the  mass 
of  water  brought  by  the  pqlar  currents  arrives 
at  the  equator  —  coming  as  it  does  from  regions 


CURRENTS.  73 

where  it  naturally  has  less  velocity  —  it  does 
not  at  once  acquire  the  velocity  of  the  earth  at 
the  equator ;  and  since  the  rotation  of  the  earth 
is  from  west  to  east,  this  portion  of  the  water 
lagging  behind,  forms  a  stream  or  current  which 
has  an  apparent  motion  from  east  to  west,  that 
is  to  say,  apparent  as  regards  the  earth,  but 
real  in  relation  to  the  adjacent  land  and  water. 
The  trade  winds,  which  in  this  zone  blow  per- 
petually in  the  same  direction,  lend  their  aid  in 
maintaining  the  equatorial  current. 

An  extensive  system  of  currents  appears  to 
commence  in  the  Antarctic  Ocean.  A  current 
of  cold  water  flowing  northwards  joins  the  equa- 
torial current  in  the  Pacific.  Entering  the  In- 
dian Ocean,  it  maintains  its  westerly  course 
until  it  approaches  the  shores  of  Africa.  Then 
bending  southwards,  it  rushes  through  the  Mo- 
zambique Channel,  and  doubling  the  Cape  of 
Good  Hope,  travels  northwards  until  it  arrives 
at  the  Bight  of  Benin.  This  current  there  joins 
the  equatorial  current,  and  crossing  the  Atlantic 
from  the  coast  of  Guinea  to  that  of  Brazil,  it  is 
divided  into  two  branches  by  the  projecting 
headland  at  Cape  St.  Roque.  The  smaller 
branch  flows  southwards  along  the  eastern  coast 
of  South  America,  where  it  meets  the  Antarctic 
current  to  which  it  owed  its  commencement,     r^ 


74 


TIDES,    WAVES,    AND    CURRENTS. 


The  northerly  branch  of  this  current  skirts  the 
shores  of  Brazil  and  Guiana,  where  it  receives 
the  waters  of  the  rivers  Amazon  and  Oronoco. 
After  passing  the  island  of  Trinidad,  this  great 
oceanic  current  enters  the  Gulf  of  Mexico.  The 
waters  there  acquire  the  high  temperature  of 
about  88°  Fahrenheit.  Sweeping  round  that 
extensive  inland  sea,  they  again  pour  forth  into 
the  Atlantic,  forming  the  most  powerful  of 
known  currents,  called  the  Gulf  Stream.  On 
issuing  from  the  Gulf  of  Mexico  this  current 
of  warm  water  rushes  with  considerable  force 
through  the  straits  of  Bahama.  Then  taking 
a  northward  course,  it  travels  along  the  eastern 
shores  of  North  America,  until  it  approaches 
Newfoundland,  where  it  is  turned  to  the  east- 
ward, by  an  opposing  cold  current  which  sets  in 
from  Baffin's  Bay.  It  now  maintains  an  easter- 
ly direction,  and  crossing  the  Atlantic  arrives 
at  the  Azores  in  about  twenty-eight  days,  and 
divides  its  waters  on  the  coast  of  France  and 
Spain ;  a  portion  goes  southward,  and  at  length 
joins  the  grand  current  which  sets  from  the 
coast  of  Guinea,  while  a  portion  travels  north- 
wards. Thence  it  extends  to  the  Bay  of  Biscay, 
and  travelling  northwards  skirts  the  western 
coasts  of  Europe,  sometimes  wafting  to  and 
depositing  on  its  shores  and  also  on  the  western 


THE    ATMOSPHERE. 


75 


coasts  of  the  British  isles  the  products  of  tropi- 
cal America,  and  probably  imparting  to  the 
whole  of  the  Northern  Ocean  some  portion  of 
its  more  elevated  temperature. 


/ 


IX.  THE  ATMOSPHERE. 


The  Earth  is  surrounded  by  its  atmosphere, 
which  like  a  transparent  covering  envelopes  it 
and  revolves  with  it.  This  atmosphere  is  con- 
sidered to  extend  to  the  height  of  about  forty  or 
fifty  miles,  its  height  being  greater  at  the  equa- 
tor than  at  the  poles. 

The  air,  which  expands  into  and  forms  this 
atmosphere,  is  an  elastic  fluid  consisting  of  a 
mixture  (not  a  compound)  of  oxygen  gas  and 
nitrogen  or  azotic  gas,  in  the  regular  proportions 
of  twenty-one  parts  of  oxygen  to  seventy-nine 
parts  of  nitrogen.  The  atmosphere  also  con- 
tains a  small  quantity  of  carbonic  acid  gas,  and 
a  yet  smaller  quantity  of  ammonia.  Water  in 
the  form  of  vapor,  in  which  state  it  is  invisible, 
is  also  always  present  in  the  atmosphere,  though 
the  quantity  is  subject' to  great  variations.     All 


76  THE    ATMOSPHERE. 

these  substances  move  freely  among  each  other, 
and  are  continually  changing  places  ;  the  oxygen 
being  ever  ready  to  perform  the  office  assigned 
to  it  of  sustaining  life  and  combustion;  the  car- 
bonic acid,  to  promote  the  growth  of  vegetation ; 
the  nitrogen,  to  perfect  the  fruits  of  the  earth ; 
and  the  vapor,  to  descend  to  the  thirsty  ground 
in  the  form  of  showers  and  dew. 

The  air  being  elastic  is  therefore  capable  of 
expansion,  or  of  spreading  in  all  directions  ;  and 
also  of  being  compressed  into  a  smaller  space  ; 
and  when  compressed,  becomes  more  dense,  or 
thicker,  and  consequently  is  heavier.  And  thus, 
if  a  closed  vessel  of  any  size  be  filled  with  com- 
pressed air,  and  another  of  similar  size  be  filled 
with  air  which  has  not  been  compressed,  the 
former  is  found  to  have  more  weight  than  the 
latter,  in  proportion  to  the  degree  of  compres- 
sion. 

The  consequence  of  this  weight  or  elasticity 
of  the  air  is,  that  it  is  much  lighter  and  thinner 
in  the  upper  regions  of  the  atmosphere  than 
nearer  the  earth's  surface  :  for  at  the  level  of  the 
sea,  the  air  has  the  weight  of  the  whole  atmos- 
phere above  it  to  compress  it  and  give  it  greater 
density ;  but  at  an  elevation  of  10,000  feet,  the 
pressure  from  above  being  diminished,  the  air  is 
less   dense    and  lighter:   because  its   elasticity 


ITS    WEIGHT.  77 

causes  it  readily  to  become  compressed  near  the 
level  of  the  sea,  and  to  expand  in  the  upper  re- 
gions of  the  atmosphere.  And  hence,  air  is 
thinner  or  more  rarefied  on  elevated  mountains 
than  at  the  level  of  the  sea ;  the  decrease  in 
density  being  in  regular  proportion,  according 
to  the  height  above  the  sea  level.  In  conse- 
quence of  the  air  becoming  so  much  thinner  or 
more  rare  at  great  elevations,  travellers  who 
ascend  lofty  mountains  usually  find  their  res- 
piration much  affected,  and  they  are  sometimes 
compelled  to  seek  relief  by  throwing  themselves 
on  the  ground,  which  enables  them  to  breathe 
more  freely. 

The  weight  of  the  atmosphere  at  the  level  of 
the  sea  is  equal  to  about  fourteen  pounds  and  a 
half  on  every  square  inch.  This  is  called  the 
weight  of  an  atmosphere,  and  is  balanced  by  a 
column  of  mercury  thirty  inches  in  height ;  but 
at  the  elevation  of  18,000  feet,  it  would  be  bal- 
anced by  a  column  only  fifteen  inches  in  height, 
at  that  of  36,000  by  one  only  seven  inches  and 
a  half  in  height,  and  so  on.  It  is  on  this  prin- 
ciple that  the  mercurial  barometer  has  been 
constructed ;  and  since  the  mercury  in  the  ba- 
rometer is  found  (with  slight  local  variations) 
to  stand  at  the  same  point  at  all  places  at  the 
level  of  the  sea,  and  to  fall  in  a  regular  ratio  as 


78  THE    ATMOSPHERE. 

we  ascend  above  that  level,  this  instrument 
iorms  a  most  useful  standard  for  measuring  the 
altitude  of  any  place,  either  mountain,  hill,  or 
plain,  to  which  a  barometer  can  be  carried. 
The  mercury  is  considered  to  fall  one  degree 
in  about  every  950  feet.  Baron  de  Humboldt, 
when  he  visited  Chimborazo  in  the  Andes, 
found  that  at  the  level  of  the  sea  near  that 
mountain  the  barometer  stood  at  303 ;  but  at 
the  height  to  which  he  ascended,  it  fell  to  four- 
teen inches,  eight  lines;  and  accordingly  he 
came  to  the  conclusion  that  the  elevation  he 
had  attained  was  19,3o3  feet.  Air  is  subject 
to  variations  in  its  density,  even  at  the  same 
level,  being  affected  by  the  presence  of  vapor 
in  the  atmosphere,  by  currents  of  wind,  by  elec- 
trical action,  &c. ;  and  hence  the  mercury  usually 
falls  at  the  approach  of  rain,  of  wind,  or  of  a 
thunder-storm,  and  hence  the  daily  and  even 
hourly  fluctuations  which  take  place  in  the 
barometer. 

The  temperature  of  the  air  likewise  diminishes 
as  we  ascend  above  the  level  of  the  sea.  The 
rate  of  decrease  does  not  appear  to  be  absolutely 
regular,  but  is  considered  to  be  about  one  degree 
of  Fahrenheit's  thermometer  for  about  every  340 
feet ;  and  accordingly  (though  variations  occur 
from  local   causes)    the  thermometer  generally 


WINDS.  79 

stands  lower  in  elevated  districts,  than  in  those 
nearer  the  sea  level  in  the  same  latitude ;  and 
hence  it  is,  that  even  in  the  hottest  regions  of 
the  earth,  very  lofty  mountains  are  covered  with 
perpetual  ice  and  snow. 


i 


WINDS. 


The  aerial  currents  called  winds  appear  to  be 
caused  by  partial  changes  in  the  density  of  the 
atmosphere,  in  great  measure  arising  from  the 
different  distribution  of  heat  in  various  parts  of 
the  earth's  surface.  When  air  is  warmed  by 
the  heat  of  the  sun  or  any  other  cause,  it  be- 
comes less  dense,  and  the  space  it  occupies  has 
therefore  more  capacity,  or  more  room  to  admit 
an  additional  portion  of  air.  If  an  adjacent 
stratum  of  air  be  cooler,  it  will,  on  coming  in 
contact  with  the  warmer  air,  expand  and  pour 
into  the  space  occupied  by  the  latter,  thus  form- 
ing a  current,  or  wind.  The  greater  the  differ- 
ence between  the  temperature  of  the  one  por- 
tion of  air  and  the  other,  the  greater  will  be  the 
force  with  which  the  cold  portion  will  rush  into 
the  space  occupied  by  the  warm  portion,  or,  in 
other  terms,  the  more  violent  will  be  the  wind. 
This    is   well   displayed  in   the   violent  winds 


80  THE    ATMOSPHERE. 

which  in  some  warm  regions  almost  daily  rush 
down  from  the  adjacent  mountains  into  the 
plains,  as  soon  as  the  latter  become  heated  by 
the  mid-day  sun. 

In  the  United  States,  and,  generally  speaking, 
in  temperate  climates,  the  winds  are  variable  ; 
but  in  some  parts  of  the  globe  they  blow  with 
great  regularity,  and  in  others  are  subject  to 
periodical  changes. 

The  most  remarkable  permanent  winds  are 
those  termed  the  trade-winds.  The  air  at  the 
surface  of  the  sea  between  the  tropics  is  much 
warmer  than  in  high  northern  and  southern  lati- 
tudes ;  and  since  air  expands  and  becomes  less 
dense  when  heated,  the  light  warm  ,air  in  inter- 
tropical regions  perpetually  rises  from  the  sur- 
face, and  its  place  is  as  perpetually  supplied  by 
the  colder  air,  which  glides  in  from  the  regions 
both  to  the  north  and  to  the  south  of  the  tropics. 
If  it  were  not  for  the  earth's  rotation  on  its  axis, 
these  would  be  merely  northerly  and  southerly 
winds;  but,  like  the  equatorial  currents  in  the 
ocean,  these  cool  currents  of  air,  coming  from 
regions  which  have  not  an  equal  •velocity  of 
rotation  with  the  air  at  the  equator,  pause  and 
hang  back,  and  thus  these  aerial  currents  ac- 
quire a  westerly  direction,  forming  permanent 
north-easterly  winds  in  the  northern  hemisphere, 


WINDS.  81 

and  south-easterly  in  the  southern.  In  the  im- 
mediate vicinity  of  the  equator,  where  the  two 
aerial  currents  from  the  north  and  south  meet, 
they  so  completely  counteract  each  other,  that  a 
zone  about  five  degrees  and  a  half  in  width  ex- 
ists, which  is  comparatively  calm  and  free  from 
any  prevalence  of  easterly  winds,  though  subject 
to  storms  of  thunder  and  lightning.  This  zone 
is  called  the  variables.  The  trade-winds  form 
two  great  belts,  extending  on  either  side  of  this 
zone,  to  north  and  south  latitude  28°.  A  devia- 
tion from  their  regularity  is  caused  by  the  prox- 
imity of  land ;  and  they  are  less  regular  in  the 
Pacific*  than  in  the  Atlantic,  and  less  steady  in 
the  North  than  in  the  South  Atlantic. 

While  this  interchange  of  air  gives  rise  to  -east- 
erly winds  in  the  tropical  seas,  it  at  the  same 
time  causes  westerly  winds  to  prevail  in  higher 
latitudes.  The  warm  air  which  has  changed 
places  with  the  cooler  northern  and  southern 
air,  carries  with  it  the  velocity  belonging  to  its 
former  situation  near  the  equator,  into  regions 
where  the  earth's  surface  moves  at  a  slower  pace, 

*  The  innumerable  islands  of  this  ocean  will  account  for  this 
want  of  regularity,  while  the  fact  that  the  westward  current 
traverses  the  South  Atlantic  may  not  be  without  weight  in  de- 
termining the  reason  of  the  greater  uniformity  of  the  trade-wind 
in  that  ocean. 

6 


04  THE    ATMOSPHERE. 

and  consequently,  as  this  air  travels  northwards 
or  southwards,  it  moves  at  a  more  rapid  pace 
than  that  portion  of  the  earth's  surface  it  now 
occupies,  thus  giving  rise  to  the  south-westerly 
gales  so  prevalent  in  our  latitude,  and  to  the 
north-westerly  gales  of  the  same  portion  of  the 
southern  hemisphere. 
^C  The  monsoons,  or  periodical  winds  of  the  In- 
dian Ocean,  appear  to  owe  their  origin  to  the 
same  cause  which  gives  rise  to  the  trade-winds, 
though  they  acquire  a  different  character  in  con- 
sequence of  the  proximity  of  land.  In  the  south- 
ern portion  of  the  Indian  Ocean,  which  is  remote 
from  this  cause  of  disturbance,  the  trade-wind 
blows  with  its  wonted  regularity ;  but  in  the  seas 
occupying  the  region  between  the  eastern  coast 
of  Africa  on  the  one  side,  and  the  Malayan  pe- 
ninsula and  Sumatra  on  the  other,  the  course  of 
the  trade-wind  is  reversed  for  half  the  year.  This 
change  occurs  from  April  to  October :  the  sun  at 
that  period  being  vertical  north  of  the  equator, 
and  the  land  in  the  adjacent  regions  acquiring  in 
consequence  a  high  temperature,  and  the  air  over 
the  sea  being  cooler  than  that  over  the  land,  a 
south-west  wind  prevails.  This  wind,  called  the 
south-west  monsoon,  commences  at  about  three 
degrees  south  of  the  equator,  and,  passing  over 
the  ocean,  arrives  charged  with  moisture,  and 


WINDS. 


83 


accordingly  usually  deposits  copious  supplies  of 
rain  in  India  and  some  of  the  adjoining  territo- 
ries. In  the  remaining  half  of  the  year,  that  is, 
from  October  to  April,  the  wind  resumes  the 
ordinary  north-easterly  direction  of  the  trade- 
wind. 

Sea  breezes  occur  in  regions  bordering  on  the 
sea   in   hot   climates.     They   are   produced   by 
causes  similar  to  those  which  give  rise  to  the 
south-west  monsoon.     The  surface  of  the  land 
being  more  heated  during  the  day  than  that  of  the 
sea,  and  the  air  consequently  becoming  rarefied, 
the  cooler  heavier  air  rushes  in  from  the  surface 
of  the  sea,  thus  giving  rise  to  the  sea  breeze. 
This  usually  commences  at  about  ten  o'clock  in 
the  morning,  and  continues  throughout  the  day 
until  about  six  o'clock  in  the  afternoon,  when  it 
gradually  sinks   away.     In  some  situations  the 
reverse  takes  place  at  night,  the  sea  at  that  time 
retaining  a  higher  temperature  than  the  adjacent 
land  and  causing  a  land  breeze  to  spring  up. 
This  usually  commences  at  about  eight  o'clock 
in  the  evening,  and  dies  away  before  six  in  the 
morning  ;  it  is  much  fainter  and  less  regular  than 
the  sea  breeze,  and  also  of  less  common  occur- 
rence ;  for  the  sea  breeze  may  generally  be  ob- 
served in  all  warm  countries,  and  even,  in  sunny 
weather,  on  our  own  shores. 


84  THE    ATMOSPHERE. 

Hurricanes  are  storms  of  wind  which  sweep  or 
whirl  round  in  a  regular  course,  and  are  at  the 
same  time  carried  onward  along  the  surface  of 
the  globe.  In  the  northern  hemisphere  the  whirl- 
ing motion  follows  the  course  of  east,  north, 
west,  south,  to  east  again  ;  in  the  southern  hemi- 
sphere it  takes  the  opposite  course.  In  the  At- 
lantic Ocean,  the  principal  region  of  hurricanes 
lies  to  the  eastward  of  the  West  Indian  Islands. 
They  are  of  frequent  occurrence  in  the  Indian 
Ocean,  at  no  great  distance  from  the  Island  of 
Madagascar.  The  typhous  of  the  China  Seas 
and  the  ox-eye  of  the  Cape  of  Good  Hope  are 
also  considered  to  be  revolving  storms. 

The  tornadoes  of  the  western  coast  of  Africa, 
the  pamper  as  of  South  America,  and  the  storms 
called  arched  squalls,  appear  to  be  of  a  different 
character,  and  not  to  possess  a  revolving  motion. 

The  sirocco  of  Italy  and  Sicily,  and  the  solano 
of  Spain,  as  also  the  simun  or  simoon  (sometimes 
called  simoom)  of  Arabia,  and  the  harmattan  of 
Western  Africa,  are  all  winds  which  owe  their 
origin  to  the  parched  and  heated  surfaces  of 
Africa  and  Arabia.  The  principal  difference 
between  these  winds  appears  to  be,  that  the 
sirocco  and  the  solano  acquire  some  moisture  in 
their  passage  across  the  Mediterranean  Sea,  and 
therefore  do  not  possess  that  extreme  degree  of. 


VAPOR. 


85 


aridity  which  forms  the  distinguishing  character 
of  the  simun  and  the  harmattan.* 

Water  in  the  form  of  vapor  is  always  present 
in  the  atmosphere.  Warm  air  is  capable  of  hold- 
ing suspended  a  larger  quantity  of  moisture  than 
cold  air,  and  therefore  the  amount  of  vapor  present 
in  the  atmosphere  is  subject  to  great  variations. 
If  water  be  exposed  to  the  air,  it  gradually  disap- 
pears, finding  its  way  into  the  atmosphere  by  the 
process  called  evaporation.  If  not  exposed  to  the 
air,  as  for  instance,  if  kept  in  a  closely-corked  bot- 
tle, the  quantity  will  remain  undiminished  for 
years;  but  if  we  leave  the  bottle  uncorked,  the 
water  will  ere  long  be  dried  up,  or  evaporated ;  and 
if  we  pour  the  water  into  a  plate,  a  larger  sur- 
face being  thus  exposed  to  the  air,  the  process  of 
evaporation  will  be  carried  on  much  more  rap- 
idly. Warm  air  being  capable  of  holding  a 
larger  quantity  of  moisture  than  cold  air,  evapo- 
ration proceeds  more  rapidly  in  warm  than  in 
cold  weather,  and  hence  a  pond,  or  moist  garden 
mould,  will  be  dried  up  much  more  rapidly  in 
summer  than  in  winter. 

*  The  subject  of  Winds  is  becoming  better  understood  and 
more  reducible  to  law,  every  year.  It  would  be  a  triumph  of 
physical  science,  too  great  to  expect,  to  be  able  to  determine  the 
exact  sequence  of  winds  in  any  portion  of  the  earth,  and  thus  to 
predict  the  state  of  the  weather  with  certainty,  yet  we  may  be 
assured  that  our  knowledge  of  winds  is  but  in  its  infancy,  and 
that  large  discoveries  are  yet  to  be  made  in  this  direction. 


86  THE    ATMOSPHERE. 

The  fact  that  warm  air  is  capable  of  holding 
a  larger  quantity  of  moisture  than  cold  air,  ac- 
counts for  the  formation  of  dew.  A  cubic  foot  of 
air,  at  the  temperature  of  32°  (the  freezing  point), 
has  not  capacity  for  holding  more  than  two 
grains  and  a  half  of  moisture,  while  at  the  tem- 
perature of  70°,  it  will  hold  about  five  grains  and 
three-quarters;  and  in  intermediate  proportions 
between  these  temperatures.  It  will  therefore 
be  evident  that  if  the  air  become  heated  during 
the  day,  its  capacity  for  holding  vapor  being  thus 
increased,  evaporation  will  proceed  with  greater 
or  less  rapidity,  and  the  air  will  become  more  or 
less  charged  with  moisture,  according  to  the 
nature  of  the  surface  on  which  it  rests  or  over 
which  it  passes,  and  its  own  temperature.  But 
when  a  cold  night  succeeds  to  a  hot  day,  the  air 
being  no  longer  capable  of  holding  this  watery 
vapor,  it  will,  as  the  temperature  gradually  di- 
minishes, be  gradually  and  gently  deposited  in 
the  form  of  dew.  Dews  will  therefore  usually  be 
most  abundant  when  cool  nights  succeed  warm 
days,  which  in  our  climate  more  frequently  hap- 
pens in  summer  and  autumn  than  in  spring 
and  winter.  The  air  usually  becomes  much 
colder  on  clear  nights  than  when  the  skies  are 
obscured  by  clouds,  and  accordingly  dew  is  gen- 
erally more  abundantly  deposited  on  starlight 
than  on  cloudy  nights. 


DEWS.  87 

It  is  also  essential  for  the  copious  formation  of 
dew  that  the  ground,  or  other  substance  on 
which  it  is  deposited,  should  be  much  cooler 
than  the  superincumbent  air;  for  if  the  ground 
be  warm,  it  will  impart  its  temperature  to  the 
air  near  its  surface,  and  dew  will  not  be  formed. 
The  surface  of  trees,  and  of  vegetation  in  gen- 
eral, is  much  colder  than  that  of  bare  rocks,  or 
even  garden  mould,  and,  consequently,  dew  is 
more  abundantly  deposited  on  the  herbs  of  the 
field  and  the  trees  of  the  forest,  than  on  barren 
and  stony  ground.* 

When  the  surface  of  the  ground  or  water  is 
warmer  than  the  superincumbent  air,  mists  and 
fogs  are  frequently  formed.  And  since  water  and 
marshy  surfaces  cool  less  rapidly  than  dry  land, 
mists  and  fogs  are  of  more  common  occurrence 
in  low  damp  situations  than  in  dry  elevated  dis- 
tricts. They  are  formed  by  the  condensation  of 
the  vapor,  or,  in  other  terms,  its  transformation 
into  minute  drops  of  water,  which,  instead  of  de- 
scending to  the  earth  in  the  form  of  dew,  remain 
suspended  above  the  land  or  the  water.     A  re- 

*  The  pupil  must  bear  in  mind  that  those  things  which  are  the 
slowest  heated,  are  also  those  which  best  retain  their  heat  ; 
hence  rocks,  gravel  paths,  &c.  do  not  readily  receive  the  dew, 
as  they  radiate  slowly  the  little  heat  which  they  have  absorbed 
during  the  day. 


88 


THE    ATMOSPHERE. 


raarkable  stationary  fog  exists  off  the  coast  of 
Newfoundland,  which  owes  its  origin  to  the 
chilly  atmosphere  of  that  region,  and  the  com- 
parative warmth  of  the  adjacent  ocean,  the  tem- 
perature of  which  is  apparently  raised  by  the 
waters  of  the  Gulf  Stream. 

Clouds  are  formed  by  the  condensation  of  va- 
por at  considerable  but  various  elevations  in  the 
atmosphere.  Vapor  is  always  invisible  ;  clouds, 
therefore,  are  not  vapor,  but  water,  and  consist  of 
a  fine  watery  powder,  the  size  of  each  particle 
being  exceedingly  minute  ;  and  consequently 
they  are  so  light,  that  clouds  formed  of  an  accu- 
mulation of  such  particles  are  readily  borne 
forward  by  the  wind.  Clouds  are  sometimes 
suddenly  formed,  and  as  suddenly  disappear ; 
probably  owing  to  sudden  and  partial  changes  of 
temperature  in  the  region  of  the  atmosphere 
where  they  occur.  When  a  considerable  differ- 
ence of  temperature  prevails  in  the  aerial  currents, 
or  strata  of  air,  which  may  come  in  contact  in 
the  atmosphere,  a  further  condensation  takes 
place,  and  the  particles  of  this  fine  watery  pow- 
der unite  into  drops,  and  becoming  heavier,  fall 
to  the  earth  in  the  form  of  rain,  hail,  or  snow. 
When  two  strata  or  currents  of  air  of  different 
temperature,  moving  with  great  rapidity  in  op- 
posite directions,  come  in  contact,  a  sudden  and 


CLOUDS. 


89 


heavy  fall  of  rain  takes  place.  If  one  of  these 
strata  be  very  cold,  hail  may  be  formed.  Snow 
is  formed  under  the  same  circumstances  as  rain, 
only  the  formation  takes  place  in  cold  climates, 
or  at  great  elevations  in  the  atmosphere. 

Clouds  are  continually  varying  in  their  form 
and  appearance,  but  may  be  classed  under  four 
principal  heads  :  —  1,  the  cirrus  ;  2,  the  cumulus  ; 
3,  the  stratus  ;  4,  the  nimbus. 

1.  The  cirrus  is  a  light  fleecy  cloud,  resembling 
a  lock  of  hair  or  a  feather. 

2.  The  cumulus,  or  summer  cloud,  is  generally 
a  massive  cloud,  of  a  rounded  form ;  sometimes 
of  small  size,  and  sometimes  nearly  covering  the 
whole  sky ;  and  occasionally  appearing  in  the 
horizon  like  mountains  capped  with  snow. 

3.  The  stratus  is  a  horizontal  misty  cloud, 
sometimes  observed  on  fine  summer  evenings 
comparatively  near  the  ground,  and  often  cross- 
ing the  middle  regions  of  mountainous  or  hilly 
districts. 

4.  The  nimbus,  or  rain-cloud,  has  a  uniform 
gray  tint ;  it  is  fringed  at  the  edges,  when  these 
are  displayed,  but  usually  covers  the  whole  sky. 

The  region  of  clouds  is  a  zone  extending  in 
the  atmosphere  from  about  one  to  four  miles 
above  the  surface  of  the  globe.  The  most  ele- 
vated clouds  are  the  light  fleecy  clouds  which 


90 


THE    ATMOSPHERE. 


are  comprehended  under  the  name  of  cirrus,  and 
the  lowest  are  those  which  are  called  stratus. 

The  cirro-cumulus,  cirro-stratus,  and  cumulo- 
stratus  are  only  modifications  and  combinations 
of  the  above  four  classes  of  clouds. 
■>■  The  quantity  of  rain  that  falls  in  different  parts 
of  the  earth  is  very  variable  ;  though  (since  the 
amount  of  evaporation  is  augmented  by  the 
higher  temperature  of  the  atmosphere)  it  may  be 
considered  as  a  general  rule,  that  larger  quantities 
of  rain  fall  in  low  than  in  high  latitudes  ;  and  it 
appears  that  a  gradual  decrease  in  quantity  takes 
place,  as  we  recede  from  the  equator  towards  the 
poles.  In  the  island  of  Tahiti,  the  annual  fall  of 
rain  amounts  to  150  inches ;  at  Bombay,  to  80 
inches  ;  in  the  British  Isles,  to  about  25  inches  ; 
at  St.  Petersburg,  to  only  17  inches. 

Rain  is  more  abundant  in  the  New  than  in  the 
Old  World,  which  is  probably  owing  to  the  dif- 
ferent configuration  of  the  two  great  continents, 
the  longer  and  narrower  being  more  exposed  to 
the  moist  winds  from  the  sea  than  the  shorter 
and  broader.  Thus  the  annual  fall  of  rain  in 
tropical  America  amounts  to  115  inches,  whilst 
in  similar  parallels  of  latitude  in  the  Old  World 
it  does  not  exceed  76  inches.  In  the  temperate 
zone  in  the  New  World,  again,  the  annual  quan- 
tity of  rain  is  37  inches,  whilst  in  the  Old  World 
it  is  only  3l£  inches. 


RAIN.  91 

In  some  parts  of  the  earth,  extensive  tracts  ex- 
ist, where  rain  is  never  known  to  fall,  or  if  at  all, 
only  at  intervals,  and  then  in  small  quantities. 
The  rainless  districts  in  the  New  World  include 
the  flat  territories  of  Northern  Chili  and  Peru, 
some  parts  of  Mexico,  and  some  parts  of  Cali- 
fornia. In  the  Old  World,  an  extensive  rainless 
band  extends  from  the  western  shores  of  Africa 
to  the  central  regions  of  Asia,  including  the 
Great  African  Desert,  Egypt,  part  of  Arabia,  and 
the  Desert  of  Cobi.  Countries  so  circumstanced 
—  unless,  like  Egypt,  rendered  fertile  by  the 
overflowings  of  a  great  river  —  constitute  the 
most  arid  and  desolate  regions  of  the  earth.  J*^ 

The  quantity  of  rain  which  falls  in  any  region 
depends  greatly  on  local  causes,  such  as  the  va- 
riations of  the  surface,  the  prevailing  winds,  the 
proximity  of  the  ocean,  &c.  Rain  is  usually 
more  copiously  deposited  in  mountainous  and 
well-wooded  islands  than  in  any  other  descrip- 
tion of  surface,  of  which  the  island  of  Tahiti 
affords  a  striking  example  ;  for  this  beautiful 
island,  surrounded  as  it  is.  by  the  waters  of  the 
ocean,  covered  with  luxuriant  vegetation,  and 
containing  mountains  rising  to  the  height  of 
10,000  feet  above  the  level  of  the  sea,  possesses 
every  requisite  condition  for  the  copious  deposi- 
tion of  rain.     The  warmth  of  the  air  causes  a 


Ill  ■ 

t-J: 

Hi* 

'i  M 

"    i" 

HI 

;-  -i  ft 


RAIN.  93 

large  amount  of  evaporation  to  take  place  from 
the  ocean  which  surrounds  it  on  all  sides,  and 
this  vapor  becomes  condensed  by  the  cool  sur- 
face presented  by  its  elevated  and  richly  wooded 
mountains  and  hills  ;  *  and  hence  the  extraordi- 
nary quantity  of  rain  in  that  island.  The  rain- 
less district  of  Peru,  on  the  other  hand,  though  it 
borders  on  the  Pacific  Ocean,  is  flat  and  nearly 
destitute  of  trees,  whilst  on  the  inland  side  the 
Andes  rise  abruptly  to  a  great  elevation,  the 
consequence  of  which  is,  that  the  moisture 
brought  by  the  westerly  winds  from  the  ocean 
does  not  become  condensed  in  its  passage  across 
the  hot  surface  of  the  flat  districts  of  Peru,  and 
therefore  rain  scarcely,  if  ever,  falls  in  that  region, 
but  an  abundant  deposition  takes  place  on  the 
elevated  mountains  in  the  interior.  And  thus 
again,  if  elevated  hills  border  on  the  ocean  in 
any  district,  whilst  the  interior  consists  of  flat 
plains,  the  moisture  usually  is  deposited  on  the 
elevated  land,  and  the  interior  tracts  receive 
small  supplies  of  rain  ;  such  is  the  case  with  the 
rainless  portion  of  Arabia. 

The  annual  fall  of  rain  in  the  British  Isles, 
amounts,  as  has  been  stated,  to  about  25  inches ; 
but  the  quantity  differs  greatly  in  the  eastern  and 

*  The  pupil  will  see  at  once  the  analogy  between  the  formation 
of  rain  and  of  dew  in  this  respect. 


94  THE    ATMOSPHERE. 

western  districts.  The  winds  sweeping  over  the 
expanse  of  the  Atlantic  Ocean  arrive  charged 
with  abundance  of  moisture,  but  deposit  a  con- 
siderable portion  before  they  reach  the  inland  and 
eastern  districts.  Thus,  the  amount  of  rain  that 
falls  annually  at  Glasgow  is  nearly  eight  inches 
more  than  at  Edinburgh.  The  number  of  rainy 
days  in  England  is  estimated  at  about  154  in 
the  year,  and  on  the  western  coast  of  Ireland  at 
no  less  than  208.  The  amount  of  rain  does  not, 
however,  necessarily  depend  on  the  number  of 
rainy  days,  for  though  the  amount  of  rain  within 
the  tropics  is  so  much  greater,  the  number  of 
rainy  days  does  not  usually  exceed  78  or  80. 

In  New  England  the  amount  of  rain  which 
falls  is  greater  than  in  the  British  Isles,  being 
about  38  inches.  The  quantity  decreases  as  we 
go  westward,  and  at  St.  Louis  it  is  32  inches. 
The  southern  and  western  states  are,  however, 
largely  affected  by  the  warm  and  moist  winds 
from  the  Gulf  of  Mexico. 

In  intertropical  regions  the  rains  follow  the 
sun ;  that  is,  when  he  is  north  of  the  equator, 
the  rains  prevail  in  the  northern  tropic,  and  when 
he  is  south  of  that  line,  in  the  southern ;  this 
forms  the  rainy  and  dry  seasons,  to  which  coun- 
tries so  situated  are  subject.  This  does  not, 
however,  apply  to  the  whole  of  the  intertropical 


CLIMATE. 


95 


regions,  for  in  a  zone  extending  from  the  fifth  to 
the  tenth  degree  of  latitude  on  each  side  of  the 
equator,  there  are  two  rainy  and  two  dry  seasons. 
In  the  narrow  belt,  called  the  variables,  which  is 
situated  between  the  regions  of  the  north  and 
south  trade-winds,  rain  is  almost  incessant,  ac- 
companied by  thunder  and  lightning.  In  inter- 
tropical countries,  during  the  rainy  season,  the 
rain  pours  down  in  such  torrents,  that  a  larger 
quantity  sometimes  falls  in  a  few  hours  than  in  a 
whole  month  in  the  British  Isles. 

Beyond  the  tropics  some  countries  possess 
rainy  and  dry  seasons,  and,  generally  speaking, 
greater  abundance  of  rain  falls  at  particular  pe- 
riods of  the  year,  though  to  the  north  of  the  45th 
parallel  of  latitude  the  rains  are  usually  variable, 
of  which  we  meet  with  an  example  in  the  British 
Isles.* 


* 


X.  CLIMATE. 


The  term  climate  is  used  to  express  the  com- 
bination of  temperature  and  moisture  which  pre- 

•  For  more  enlarged  generalizations  and  more  extensive  de- 
tails on  the  subject  of  rains,  the  reader  will  consult  that  very 
valuable  book,  Guvot's  Earth  and  Man. 


96  CLIMATE. 

vails  at  any  particular  place,  or,  in  more  familiar 
terms,  the  prevailing  weather. 

The  most  prominent  causes  of  diversity  of 
climate  are,  the  heat  of  the  sun,  the  relative  posi- 
tion of  land  and  water,  and  the  elevation  of  land 
above  the  level  of  the  sea.  To  these  may  be 
added,  as  producing  considerable  though  less 
marked  effects,  the  nature  of  the  soil,  the  prevail- 
ing winds,  the  position  of  mountain  ranges,  and 
the  currents  of  the  ocean. 

The  sun  is  the  grand  agent  in  diffusing  heat 
over  the  surface  of  the  globe,  the  temperature  of 
any  part  being  almost  wholly  dependent  on  its 
exposure  to  his  rays.  Whilst  the  sun  is  above 
the  horizon  of  any  place,  that  place  is  receiving 
heat ;  and  when  the  sun  is  below  the  horizon,  it 
is  parting  with  heat  by  the  process  called  radia- 
tion, that  is,  the  emission  of  heat  through  the 
atmosphere  into  the  regions  of  space.  When- 
ever, therefore,  the  sun  remains  more  than  twelve 
hours  out  of  the  twenty-four  above  the  horizon 
of  any  place  and  consequently  less  than  twelve 
hours  below,  the  general  temperature  of  that 
place  will  be  above  average ;  and  when  the  re- 
verse occurs,  it  will  be  below  average. 

In  consequence  of  the  daily  rotation  of  the 
earth,  successive  portions  of  its  surface  are  pre- 
sented to  the  sun's  rays ;  and  owing  to  the  incli- 


CLIMATE.  97 

nation,  or  slanting  position  of  the  earth  in  its 
orbit,  the  northern  and  southern  hemispheres  are 
brought  alternately  more  directly  under  the  solar 
influence,  *  and  thus  by  this  admirable  and  bene- 
ficial arrangement  the  high  temperature  of  the 
tropical  zone  is  moderated,  and  heat  more  gen- 
erally diffused  over  the  earth's  surface.  The 
power  of  the  sun's  rays  is  great,  in  proportion  to 
the  vertical  or  upright  direction  in  which  they 
strike  the  earth ;  f  and  if  the  sun's  rays  had  been 
permanently  vertical  in  equatorial  regions,  the 
heat  in  those  parts  of  the  earth  would  have  been 
greatly  more  intense,  and,  on  the  other  hand,  the 
yet  more  slanting  rays  of  the  sun  in  higher 
latitudes  would  not  have  possessed  sufficient 
power  to  ripen  the  fruits  of  the  earth  in  the  pres- 
ent temperate  zones,  nor  should  we  have  enjoyed 
the  grateful  change  of  spring,  summer,  autumn, 
and  winter. 

We  have  seen  that  the  earth  has  been  artifi- 
cially divided  into  five  zones  ;  the  torrid,  the  two 
temperate,  and  the  two  frigid  zones.  If  the 
temperature  of  any  place  depended  solely  on 
the  heat  of  the  sun,  this  might  convey  a  tolera- 
bly accurate  view  of  the  respective  climates  in 

*  See  plate  on  page  8. 

t  It  is  a  singular  fact  that  the  earth  is  three  millions  of  miles 
nearer  the  sun  in  winter  than  in  summer. 
7 


y»  CLIMATE. 

those  divisions  of  the  globe  ;  but  it  is  so  greatly 
modified  by  other  circumstances,  that  considera- 
ble differences  prevail  in  countries  situated  in  the 
same  parallels  of  latitude. 

The  relative  position  of  land  and  water  forms 
one  leading  cause  of  the  diversity  of  climate. 
The  waters  of  the  ocean  are  of  very  equal  tem- 
perature, widely  differing  in  this  respect  from  the 
surface  of  the  dry  land.  This  arises  from«the 
waters  of  the  ocean  always  preserving  a  nearly 
uniform  level,  from  their  tardiness  to  become 
heated  (because  water  is  a  bad  conductor  of 
heat),  and  from  their  not  possessing  the  same 
radiating  power  as  dry  land,  so  that  they  are  not 
subject  to  be  cooled  down  during  the  absence  of 
the  sun.  The  ocean,  therefore,  has  a  tendency  to 
moderate  both  heat  and  cold  wherever  its  influ- 
ence extends.  Thus,  when  a  cold  wind  passes 
over  the  sea,  it  becomes  warmed,  and  the  rigor 
of  winter  will  be  moderated.  A  hot  wind,  on 
the  contrary,  becomes  cooled  in  passing  over  the 
sea,  and  the  summer  temperature  of  the  adjacent 
regions  will  be  lowered.  And  thus  we  find  that 
the  climate  of  islands  and  countries  bordering 
on  the  sea  usually  differs  considerably  from  that 
of  the  interior  of  continents,  the  former  generally 
experiencing  milder  winters  and  more  temperate 
summers  than  the  latter.     Such  countries   are 


CLIMATE.  99 

said  to  possess  an  insular  climate.  Thus,  the 
British  Isles  possess  an  insular  climate.  But 
when  any  region  experiences  great  severity  of 
cold  in  winter,  and  at  the  same  time  a  consider- 
able degree  of  heat  in  summer,  it  is  said  to  pos- 
sess an  excessive  climate.  The  most  striking  in- 
stances of  an  excessive  climate  are  drawn  from 
places  like  Yakutsk,  situated  in  the  depths  of 
Siberia,  where  the  difference  between  the  aver- 
age temperature  of  winter  and  of  summer 
amounts  to  the  astonishing  sum  of  101.° 

The  effect  produced  on  climate  by  the  relative 
position  of  land  and  water  is  exhibited  on  a 
large  scale  in  the  temperate  zones  of  the  northern 
and  southern  hemispheres.  The  space  occupied 
by  the  waters  of  the  ocean  in  the  southern  hemi- 
sphere, is  far  greater  than  in  the  northern,  and 
consequently  a  much  more  even  temperature 
prevails  in  the  regions  occupying  that  portion 
of  the  globe,  than  in  those  in  the  northern  hemi- 
sphere. 

The  elevation  of  land  above  the  level  of  the  sea 
forms  another  leading  cause  of  the  diversity  of 
climate.  A  gradual  decrease  in  temperature  takes 
place  as  we  ascend  above  the  level  of  the  sea, 
until  we  attain  a  point  where  perpetual  congela- 
tion takes  place.  This  line,  which  is  called  the 
snow-line,  or  line  of  perpetual  snoiv,  varies  in  dif- 


100  CLIMATE. 

ferent  latitudes,  and  sometimes,  owing  to  the 
different  causes  which  may  give  rise  to  diversity 
of  climate,  the  height  of  the  snow-line  differs  at 
places  in  similar  latitudes.  As  a  general  rule, 
however,  it  may  be  considered,  that  a  gradual 
decrease  in  the  elevation  of  the  snow-line  above 
the  level  of  the  sea  takes  place  as  we  recede 
from  the  equator  towards  the  poles.  The  height 
of  the  snow-line  within  the  tropics  varies  from 
16,000  to  17,000  feet  above  the  level  of  the  sea  ; 
and  (in  the  northern  hemisphere)  this  line  de- 
scends to  the  very  level  of  the  sea  at  about  lati- 
tude 80°. 

The  annexed  tabular  view  of  the  snow-line  in 
different  latitudes  may  convey  a  general  idea  of 
the  limits  of  perpetual  congelation  in  the  north- 
ern hemisphere. 

It  will  be  perceived  that  the  snow-line  is  higher 
at  the  distance  of  twenty  degrees  from  the  equa- 
tor, than  at  the  equator  itself.  This  is  explained 
by  the  circumstance,  that  the  sun  at  the  equator 
is  never  more  than  twelve  hours  above  the  hori- 
zon ;  whereas,  near  the  tropics,  the  longest  days 
are  thirteen  hours  and  a  half  in  length  ;  and  as 
the  sun  at  that  period  of  the  year  is  vertical,  or 
nearly  so,  in  that  portion  of  the  globe,  the  summer 
heat,  on  which  the  line  of  perpetual  snow  de- 
pends, is  greater  than  immediately  under  the 
equator. 


LATITUDE. 
30         40         50 


TABULAR  VIEW  OF  THE  SNOW-LINE  IN  DIFFERENT 
LATITUDES  IN  THE  NORTHERN  HEMISPHERE. 


102  CLIMATE. 

The  gradual  decrease  of  temperature  which 
takes  place,  according  to  the  elevation  of  land 
above  the  level  of  the  sea,  has  a  very  beneficial 
effect  in  diversifying  the  climates  over  the  earth's 
surface,  and  in  adapting  it  to  the  growth  and 
sustenance  of  an  almost  endless  variety  of  plants 
and  animals.  In  intertropical  regions,  districts 
which  are  situated  near  the  level  of  the  sea  pos- 
sess an  extremely  high  temperature  ;  and  unless 
furnished  with  most  copious  supplies  of  rain, 
present  a  highly  arid  and  parched  aspect,  like 
Peru ;  but,  on  the  contrary,  if  rain  falls  abun- 
dantly, they  are  covered  with  the  most  luxuriant 
vegetation,  like  the  fertile  lowlands  of  Guiana. 
At  the  elevation  of  3000  or  4000  feet,  the  heat 
becomes  less  intense,  and  a  change  takes  place 
in  the  productions  of  the  soil.  At  that  of  7000 
or  8000,  the  vegetation,  and  in  great  measure  the 
climate,  resemble  that  of  temperate  countries. 
At  still  greater  elevations,  the  climate  and  plants 
are  similar  to  those  of  arctic  regions ;  and  at 
length  the  line  of  perpetual  congelation  is 
reached,  where  nothing  meets  the  eye  but  bare 
rocks  and  accumulations  of  ice  and  snow. 

In  warm  latitudes,  the  snow-line  is  found  to  be 
higher  on  mountains  which  inclose  or  border  on 
elevated  table  lands,  than  on  isolated  mountains, 
or  on  such  as  rise  precipitously  from  low  plains,  .s 


CLIMATE. 


103 


This  appears  to  be  caused  by  radiation  from 
the  elevated  plains;  for  these,  having  become 
heated  during  the  day,  radiate  or  part  with  this 
heat  during  the  absence  of  the  sun,  and  thus 
tend  to  maintain  the  temperature  of  the  moun- 
tains in  their  vicinity  during  the  night,  whereas 
isolated  mountains,  being  surrounded  by  the  at- 
mosphere, part  with  heat,  instead  of  receiving  it, 
during  the  sun's  absence. 

The  Himalaya  Mountains  afford  a  striking  ex- 
ample of  the  effect  thus  produced  by  an  elevated 
table-land.  On  the  southern  side  of  that  mighty 
range,  in  N.  lat.  30,  the  mountains  rise  directly 
from  a  flat  country,  not  more  than  1000  feet 
above  the  level  of  the  sea,  covered  with  a  close 
jungle,  which  tends  to  cool  the  superincumbent 
air ;  and  on  this  side  of  the  mountains  the  height 
of  the  snow-line  does  not  exceed  12,000  or  13,000 
feet.  On  the  northern  side  of  the  same  vast 
mountain  range,  the  elevated  table-land  of  Tibet 
extends,  rising  to  the  height  of  15,000  feet  above 
the  level  of  the  sea ;  and  in  the  vicinity  of  this 
great  plain,  the  snow-line  reaches  the  height  of 
17,000  feet  above  the  level  of  the  sea.  In  very 
cold  climates  the  reverse  takes  place :  ice-covered 
table-lands'  have  a  tendency,  by  absorption  of 
heat,  to  lower  the  temperture  of  mountains 
which  are  situated  near  them;  for  the  tempera- 


104 


CLIMATE. 


ture  of  isolated  mountains  in  icy  regions  is  some- 
times found  to  be  higher  than  that  of  the  plains 
at  their  base. 

The  nature  of  the  soil  produces  some  effect  on 
the  climate  of  any  region.  Sandy  soils  are  sub- 
ject to  become  rapidly  and  intensely  heated,  and 
when  the  sun's  rays  are  withdrawn,  they  rapidly 
radiate  and  part  with  the  heat  they  have  acquired, 
thus  increasing  the  general  temperature  of  the 
surrounding  districts.  Clayey  soils,  on  the  other 
hand,  become  slowly  heated,  and  as  slowly  part 
with  heat.  Swampy  ground  chills  the  air,  and 
extensive  forests  produce  a  similar  effect;  and 
thus,  cultivation  not  unfrequently  causes  a 
change  in  the  climate  of  a  country  ;  for  the 
draining  of  marshes  and  the  clearing  of  dense 
forests  may  raise  the  winter  temperature  of  a 
cold  country,  as  has  been  effected  in  some  parts 
of  North  America,  whilst  irrigation  and  the  cul- 
ture of  trees  may  tend  to  improve  and  moderate 
the  climate  of  hot  dry  lands,  as  has  been  expe- 
rienced, though  hitherto  on  a  small  scale,  in 
some  parts  of  California. 

The  prevailing  winds  produce  considerable 
effects  on  the  climate  of  any  region.  Countries 
where  the  prevailing  winds  sweep  across  a  wide 
expanse  of  ocean  are  not  subject  to  extremes  of 
heat  and  cold.     Thus,  the  climate  of  the  British 


CLIMATE.  105 

Isles  is  moderated,  because  the  most  prevalent 
winds  pass  over  the  Atlantic  Ocean.  In  the 
eastern  portion  of  the  New  England  States  the 
south  wind  is  marked  for  its  warmth.  This 
comes  in  from  the  Gulf  Stream  and  the  Ocean. 
Winds  which  traverse  large  tracts  of  land  vary 
in  character  according  to  the  nature  of  the  sur- 
face over  which  they  pass.  Hence  in  the  Atlan- 
tic States,  the  west  and  the  north  winds  are  dry 
and  cold. 

The  position  of  mountain  ranges  also  produces 
considerable  effect  on  the  climate  of  any  region, 
especially  when  elevated  ridges  extend  from  east 
to  west,  and  thus  either  form  a  screen  from  the 
north,  or  leave  a  country  unsheltered  in  that  di- 
rection. Thus,  the  Carpathian  Mountains  screen 
Hungary  from  the  cold  blasts  of  the  north,  and 
consequently  that  territory  enjoys  a  remarkably 
mild  climate ;  whilst  Poland,  which  is  situated 
to  the  north  of  that  range,  and  therefore  unpro- 
tected from  those  piercing  winds,  suffers  from  a 
very  cold  and  humid  climate. 

The  currents  of  the  ocean  form  very  influential 
causes  of  the  diversity  of  climate.  The  polar 
currents,  as  we  have  already  seen,  carry  towards 
the  tropics,  not  only  vast  streams  of  cool  water, 
but  also  floating  masses  of  ice,  which  tend  in  a 
great  measure  to  lower  the  temperature  of  the 


106  CLIMATE. 

regions  near  which  their  course  extends.  The 
Gulf  Stream,  on  the  other  hand,  traverses  the 
Atlantic  Ocean,  carrying  with  it  a  high  temper- 
ature, which  it  imparts  to  Western  Europe,  and 
in  all  probability  to  the  whole  of  the  Northern 
Ocean.      W^^.- 

The  waters  of  the  Gulf  Stream  bear  with  them 
from  the  Gulf  of  Mexico  large  quantities  of  a 
species  of  sea-weed  called  sargasso;  this  accu- 
mulates (probably  owing  to  the  meeting  of  some 
currents)  in  a  portion  of  the  ocean  lying  between 
the  33d  and  35th  parallels  of  north  latitude,  and 
covers  an  area  extending  about  2000  miles  from 
east  to  west,  and  350  from  north  to  south. 
The  water  in  this  tract  of  the  ocean  is  nearly 
stagnant,  and  being  continually  supplied  with 
fresh  streams  of  water  which  have  become 
heated  in  the  Gulf  of  Mexico,  its  temperature 
is  maintained  to  the  height  of  from  7°  to  10° 
above  that  of  the  Atlantic  in  the  same  latitude. 
This  is  called  the  Sea  of  Sargasso,  or  the  Re- 
cipient of  the  Gulf  Stream,  and  there  appears 
reason  to  conclude,  that  this  mass  of  warm 
water  materially  affects  the  climate  of  the  re- 
gions to  which  its  influence  extends,  both  in 
Europe  and  North  America. 

The  causes  which  produce  diversity  of  climate 
being  so  various,  great  difference  of  temperature 


CLIMATE.  107 

is  found  to  prevail  in  similar  parallels  of  latitude, 
and  no  rule  can  be  laid  down  relative  to  the 
climates-  on  the  earth's  surface.  It  may,  how- 
ever, be  considered  that,  generally  speaking,  the 
eastern  districts  of  both  the  Old  and  New  Con- 
tinents possess  more  excessive  climates  than  the 
western  districts  of  either ;  that  the  climate  in 
the  interior  of  continents  is  more  excessive  than 
either;  and  that  islands  have  a  more  equable 
or  less  variable  temperature  than  large  masses  of 
land. 

In  intertropical  regions,  comparatively  little 
variation  occurs  in  the  temperature  throughout 
the  year;  in  some  places  there  being  scarcely 
more  than  four  -degrees  between  the  average 
temperature  of  the  warmest  month  and  that  of 
the  coldest  month.  In  temperate  zones  the  dif- 
ference is  usually  much  greater.  Thus,  in  Lon- 
don, the  mean  summer  temperature  is  about  63°  ; 
and  the  mean  winter  temperature  is  about  39i°  ; 
the  difference  between  the  mean  summer  and 
winter  temperature  being  twenty-three  degrees 
and  a  half.  In  New  York,  the  mean  summer 
temperature  is  about  71°,  and  the  mean  winter 
temperature  about  30°,  making  a  difference  of 
forty-one  degrees. 

With  the  view  of  ascertaining  the  general  dis- 
tribution of  heat  over  the  surface  of  the  globe, 


108  CLIMATE. 

observations  relative  to  the  mean  annual  tem- 
perature of  various  portions  of  the  earth  have 
been  made,  and  lines  called  isothermal  lines,  or 
lines  of  equal  temperature,  are  traced  on  the  globe, 
indicating  the  various  points  on  the  earth's  sur- 
face where  the  same  mean  annual  temperature 
has  been  observed  to  prevail.  These  lines  do 
not  coincide  with  the  equator,  or  with  the  paral- 
lels of  latitude,  places  possessing  the  same  an- 
nual temperature  being  often  situated  in  widely 
different  parallels  of  latitude.  Thus,  London 
and  New  York  possess  very  nearly  the  same 
mean  annual  temperature,  that  of  51°  ;  but  Lon- 
don is  situated  about  eleven  degrees  further 
north  than  New  York,  and,  as  we  have  just  seen, 
the  summer  and  winter  temperature  of  the  two 
cities  differs  considerably.  It  is  therefore  evident, 
that  though  these  isothermal  lines  convey  a 
general  idea  of  the  distribution  of  heat  over  the 
earth's  suface,  they  do  not  determine  the  climates 
of  the  regions  where  the  observations  have  been 
made.  Lines  indicating  the  mean  summer  and 
mean  winter  temperatures,  called  isotheral  and 
isochimenal  lines,  when  these  shall  have  been 
carried  out  on  the  surface  of  the  globe,  may  tend 
more  fully  to  accomplish  this  object. 

The  line  of  highest  temperature,  which  is  nearly 
83°,  takes  its  course  generally  to  the  north  of  the 


ELECTRICITY    AND    MAGNETISM.  109 

equator,  crossing  the  Isthmus  of  Panama,  and 
passing  through  Africa  at  about  the  11th  paral- 
lel of  latitude.  The  interior  of  the  latter  re- 
gion is  considered  as  the  hottest  portion  of  the 
earth. 

The  line  of  lowest  temperature  in  the  northern 
hemisphere,  is  not,  as  we  should  suppose,  in  the 
immediate  vicinity  of  the  North  Pole,  but  com- 
mencing at  Hudson's  Bay,  it  crosses  Greenland, 
bears  somewhat  towards  the  north,  and  after- 
wards declines  to  the  central  part  of  Siberia. 


x 


XI.  ELECTRICITY  AND  MAGNETISM. 


Electricity  produces  an  infinity  of  changes  in 
the  natural  world.  It  may  be  artificially  elicited 
or  called  forth  by  friction,  and  then  it  is  termed 
ordinary  electricity  ;  or  by  the  contact  of  certain 
substances,  and  the  action  attendant  on  this  con- 
tact, and  then  it  is  called  voltaic  or  galvanic 
electricity. 

All  substances  are  supposed  to  contain  a  cer- 


110  ELECTRICITY    AND    MAGNETISM. 

tain  portion  of  electricity,  and  if  by  friction,  or 
any  other  means,  any  substance  acquires  more 
electrical  action  than  it  would  naturally  possess, 
it  is  said  to  be  positively  electrified;  and  if,  on 
the  other  hand,  there  appears  to  be  less  electrical 
excitement  than  it  would  possess  in  its  natural 
state,  it  is  said  to  be  negatively  electrified.  Sub- 
stances, when  positively  electrified,  attract  or  draw 
towards  them  other  substances  which  are  in  a 
state  of  negative  electricity,  or  even  those  which 
are  in  a  natural  state ;  but  will  repel  or  force 
from  them  substances  which  are  positively  elec- 
trified. 

The  electrical  state  of  substances  is  easily  dis- 
turbed, and  even  without  actual  contact,  any 
substance  in  a  state  of  positive  electricity  may 
produce  negative  electricity  in  a  substance  near 
it.  The  sudden  contact  of  bodies  in  an  opposite 
state  of  electricity  is  attended  with  vivid  light, 
called  the  electric  spark,  and  accompanied  by  an 
explosion  and  shock.  This  is  exhibited  on  a 
splendid  but  awful  scale  in  the  lightning's  flash 
and  the  thunder  clap. 

The  earth  is  considered  to  be  always  in  a  state 
of  positive  electricity,  the  aw*,  when  .pure,  to  be  in 
one  of  negative  electricity.  Atmospheric  air, 
however,  is  subject  to  incessant  variations,  both 
as  to  the  character  and  degree  of  its  electrical 


ELECTRICITY    AND    MAGNETISM.  Ill 

excitement,  for  it  is  liable  to  be  affected  by  the 
evaporation  and  condensation  of  moisture,  by 
the  various  chemical  processes  which  are  con- 
tinually carried  on  in  the  natural  world,  &c,  and 
thus  the  electrical  equilibrium  of  the  atmosphere, 
or  its  natural  electrical  state,  is  subject  to  be  dis- 
turbed. This  equilibrium  will  be  restored  when 
an  explosion  has  taken  place,  and  hence  it  is  that 
in  peculiar  states  of  the  atmosphere,  thunder 
storms  act  a  beneficial  part  in  restoring  the  air 
to  a  healthy  condition,  or,  in  other  terms,  restor- 
ing the  electrical  equilibrium. 

The  intensity  of  electricity  is  greater  during 
the  day  than  at  night,  and  also  in  summer  than 
in  winter ;■  and  is  considered  to  diminish  from  the 
equator  to  the  poles. 

Electricity  is  perpetually  effecting  great  changes 
in  the  earth's  crust ;  not  perhaps  so  much  in  its 
loud  and  fearful  displays,  which  are  evident  to 
man,  as  in  its  unseen  quiet  operations  ;  in  very 
many  instances  unquestionably  acting  on  the 
principle  of  voltaic  electricity,  the  electrical  action 
in  such  cases  being  produced  by  long-continued 
electrical  currents. 

T>  rrestrial  magnetism  may  be  regarded  as  a 
peculiar  exhibition  or  state  of  electricity,  and 
may  be  considered  under  two  heads  —  viz.,  mag- 
netic direction,  and  magnetic  intensity.^ 


112       ELECTRICITY  AND  MAGNETISM. 

The  magnetic  power  of  the  loadstone  to  attract 
iron  or  steel  is  well  known ;  if  a  bar  of  iron  or 
steel  be  subjected  to  a  continued  current  or 
stream  of  electricity,  or  even  be  allowed  to  re- 
main in  contact  with  the  earth  in  a  vertical  or 
upright  position  for  a  lengthened  period,  as  old 
iron  railings  may  have  done,  it  acquires  this 
magnetic  power,  or  becomes  magnetized. 

If  a  nicely-balanced  bar  or  needle  of  magnet- 
ized steel  or  iron,  be  suspended  from  its  middle 
by  a  piece  of  untwisted  silk,  free  to  move  in  all 
directions,  both  horizontally  and  vertically,  it 
will  turn  itself  to  one  particular  position,  and  if 
disturbed,  it  will  invariably  return  to  the  same 
position,  pointing  downwards  to  the  earth  at  a 
particular  angle,  and  also  in  a  particular  north- 
ward and  southward  direction.  This  is  called 
the  magnetic  direction  of  the  needle.  If  placed 
on  a  pivot,  in  a  box  or  case,  so  as  to  confine  it 
in  a  horizontal  position,  it  will  be  found  to  as- 
sume the  same  regular  northward  and  southward 
direction ;  not  due  north  and  south,  but  north- 
ward and  southward.  At  one  period  the  mag- 
netic needle  was  supposed  to  point  so  truly  to 
the  poles  of  the  earth,  that  the  phrase,  "true  as 
the  needle  to  the  pole,"  has  become  a  proverbial 
expression ;  and  hence  the  north  and  south  ends 
of  magnets  were  termed  their  north  and  south 


MAGNETISM.  113 

poles;  and  in  fact  it  appears  that  in  1659  the 
needle  actually  pointed  thus  in  London. 

It  is  on  the  above  principle  that  the  mariner's 
compass  has  been  constructed,  which  was  sup- 
posed to  point  invariably  due  north  and  south. 
It  is  now  well  known,  not  only  that  the  mag- 
netic needle  does  not  point  due  north  and  south 
in  all  parts  of  the  globe,  but  that  it  does  not 
permanently  maintain  the  same  direction  at  the 
same  places. 

The  present  north  magnetic  pole,  or  point  to 
which  the  needle  is  directed  on  this  side  of  the 
equator,  was  found  by  Sir  James  Ross,  in  Ion. 
115°  W.  and  lat.  70°  N.,  north  of  Hudson's  Bay. 
The  magnetic  pole  of  the  southern  hemisphere 
has  not  yet  been  ascertained  with  certainty,  but 
is  with  great  probability  supposed  to  be  in  Ion. 
152°  E.  and  lat.  72°  S. 

We  have  seen  that  the  magnetic  needle,  if 
freely  suspended,  does  not  settle  itself  in  a  direc- 
tion parallel  with  the  horizon,  but  dips  or  inclines 
dov  :  this  is  called  its  dip  or  inclination. 

This  dip  or  inclination  of  the  magnetic  needle, 
like  its  declination,  differs  in  different  parts  of  the 
earth's  surface,  and,  like  that,  has  undergone 
considerable  changes  in  its  direction. 

The  observation  of  navigators  shows  that 
there  is  a  line  encircling  the  earth,  at  every  point 
8 


114  DISTRIBUTION    OF    PLANTS. 

of  which  the  needle  will  take  a  true  horizontal 
position.  This  is  called  the  magnetic  equator.  It 
is  not  a  great  circle  of  the  earth  like  the  terres- 
trial equator,  and  its  form  and  position  are 
continually  varying. 


+ 


XII.  GEOGRAPHICAL  DISTRIBUTION  OF  PLANTS. 

Plants,  in  an  almost  endless  variety  of  forms, 
are  spread  over  the  surface  of  the  globe,  afford- 
ing sustenance  to  man,  and  to  a  vast  number  of 
the  other  creatures  of  God's  hand. 

Some  plants  are  adapted  to  thrive  more  par- 
ticularly in  cold  climates,  or  in  mountain  re- 
gions ;  others  attain  the  greatest  perfection  in 
temperate  zones,  and  others  belong  exclusively 
to  the  hottest  regions  of  the  earth.  Some  plants 
will  not  flourish  unless  furnished  with  copious 
supplies  of  moisture,  whilst  others  are  so  con- 
stituted that  they  can  endure  long-continued 
drought.  Some  plants  prefer  a  clayey  soil,  oth- 
ers a  chalky  soil,  others  a  sandy  soil,  whilst  others 
grow  in  the  crevices  of  rocks.  Some  plants  are 
inhabitants  of  salt  marshes,  some  of  fresh-water 
lakes,  some  of  running  streams,  some   of  the 


CLASSIFICATION    OF    PLANTS.  115 

ocean,  and  some  of  the  dark  caverns  of  the  earth. 
We  thus  find  that  each  portion  of  the  globe  has 
its  own  appropriate  vegetable  productions,  spe- 
cially adapted  to  its  climate,  its  soil,  and  its 
elevation  above  the  level  of  the  sea. 

Plants  are  divided  with  respect  to  their  flow- 
ers into  two  departments, phcenogamous  (or  phan- 
erogamous) and  cryptogamous  ;  and  the  former  of 
these,  with  respect  to  the  structure  of  the  plants, 
into  two  classes,  endogenous  and  exogenous. 

Phaenogamous  plants  are  such  as  bear  a 
plainly  distinguishable  flower.  This  class  is 
found  almost  exclusively  in  the  torrid  zone, 
largely  in  the  temperate,  but  scarcely  at  all  in 
the  frigid  zones. 

The  cryptogamous,  or  flowerless  plants,  called 
also  a-cotyledonovs,  because  they  have  no  seed- 
leaf,  are  plants  whose  flowers  and  seeds  are 
either  so  minute  as  to  be  scarcely  discernible,  or 
are  altogether  concealed  from  our  view.  This 
class  ranks  as  the  lowest  in  the  scale  of  vege- 
table productions,  and  includes  lichens,  mosses, 
thefisngOHS  tribes,  ferns,  alga?  or  sea-weeds,  &c. 

Endogenous  plants  are  so  called  because  their 
growth  or  increase  takes  place  from  within,  and 
also  mono-cotyledonous,  because  when  their  seeds 
germinate  they  have  only  one  seed-lobe  or  leaf,  as 
may  be  observed  in  the  springing  up  of  grass, 


116  DISTRIBUTION    OF    PLANTS. 

which  belongs  to  this  class ;  it  also  includes 
wheat,  rye,  barley,  rice,  maize,  lilies,  palms,  &c. 
In  the  divisions  of  the  flowers  and  fruit  of  the 
plants  belonging  to  this  class,  the  number  three, 
or  its  multiple,  prevails.  Of  this  the  lily  forms  an 
example,  which  has  twice  three  (or  six)  petals. 

Exogenous  plants,  which  form  the  highest  class 
in  the  vegetable  world,  are  so  called  because 
their  growth  takes  place  externally,  that  is,  at  or 
near  the  surface,  and  outside  of  the  pith.  The 
yearly  increase  in  some  trees  is  so  distinctly 
marked  in  rings  or  circles,  that  their  age  can  be 
nearly  determined.  Plants  of  this  class  are  also 
called  di-cotyledonous,  because  they  have  two 
seed-lobes  or  seed-leaves,  as  may  be  seen  in 
the  mignionette,  the  laburnum,  &c,  which  be- 
long to  this  class.  The  number  five  generally 
prevails  in  the  division  of  the  parts  of  the  flow- 
ers in  this  class.  This  class  includes  a  large 
proportion  of  the  trees  of  the  forest,  and  also 
most  of  the  flowering  shrubs  and  herbs.  The 
oak,  pine,  elm,  ash,  beech,  poplar,  chestnut,  wal- 
nut, &c,  belong  to  this  class,  as  do  also  the  rose, 
mallow,  heath,  daisy,  pea,  cabbage,  &c.  &c.  j><^ 

The  number  of  different  kinds  of  exogens,  or 
exogenous  plants,  is  far  greater  than  that  of  en- 
dogens,  or  endogenous  plants.  In  tropical  regions 
the  proportion  is  about  four  to  one,  and  in  tern- 


v  TBI 

v  of   • 


iRS\ 

OF 


CLASSIFICATION    OF    PLANT 


perate  zones  about  six  exogens  to  one  endogen. 
In  the  arctic  regions,  the  proportion  is  not  above 
two  to  one,  but  in  these  regions,  forest  trees 
are  few  in  number  and  dwarfish  in  growth  ;  and 
cryptogamic  plants  are  very  abundant. 

Some  plants  are  perennial,  that  is,  live  for  a 
greater  or  less  term  of  years,  some  species  at- 
taining a  very  great  age.  The  oak  appears  to 
arrive  at  perfection  at  about  the  age  of  sixty 
years,  but  lives  for  a  much  longer  term  ;  yew 
trees  are  much  longer  lived  than  the  oak.  Some 
plants  are  annual,  springing  up,  producing  flow- 
ers and  fruit,  and  decaying  in  one  short  season. 
Other  plants  are  biennial,  usually  only  sending 
forth  stems  and  leaves  in  the  first  year,  and  per- 
fecting their  flowers  and  fruit  in  the  following 
season. 

Some  plants  are  deciduous,  or  cast  their  leaves 
in  the  autumn,  and  renew  them  in  the  spring; 
others  are  evergreen,  and  never  destitute  of  foli- 
age. The  temperate  zone  may  be  considered  as 
more  especially  the  region  of  deciduous  trees. 
The  never-ceasing  energy  with  which  vegetation 
proceeds  in  intertropical  regions  imparts  to  the 
plants  of  those  climates  a  luxuriance  unknown 
in  the  temperate  zone,  and  at  no  time  are  the 
trees  bare  of  leaves  ;  a  screen  being  thus  afforded 
to  the  inhabitants  of  those  regions,  at  all  seasons 


118  DISTRIBUTION    OF    PLANTS. 

of  the  year,  from  the  scorching  rays  of  the  sun. 
The  evergreen  trees  of  the  cold  regions  of  the 
earth  are  of  a  totally  different  character,  con- 
sisting chiefly  of  pine  and  fir  trees,  whose  needle- 
shaped  leaves  are  adapted  to  withstand  the 
rigors  of  a  northern  winter,  and  whose  thick 
foliage,  often  sustaining  a  mass  of  snow,  forms 
a  shelter  both  to  man  and  to  animals  from  the 
severe  and  long-continued  cold. 

Plants  derive  their  nourishment  from  the  at- 
mosphere and  from  the  earth.  The  leaves  of 
plants  constantly  imbibe  both  moisture  and  car- 
bonic acid  gas  from  the  atmosphere,  during  the 
hours  of  daylight,  and  more  particularly  of  bright 
sunlight.  Carbonic  acid  gas  is  a  compound 
of  carbon  and  oxygen  ;  this  carbonic  acid  gas 
the  green  parts  of  plants  have  the  power  of  de- 
composing, or  of  separating  into  its  two  component 
parts  of  carbon  and  oxygen ;  the  carbon  enters 
into  their  composition,  and  the  oxygen  is  re- 
turned pure  into  the  atmosphere.  As  plants 
possess  less  energy  in  the  shade,  or  in  dark 
gloomy  weather,  they  have  not,  under  such  cir- 
cumstances, power  to  decompose  the  whole 
amount  of  carbonic  acid  they  imbibe,  and  a 
certain  portion  of  carbonic  acid  as  well  as  of 
oxygen  is  given  out  by  the  leaves.  At  night 
they  no  longer  emit  pure  oxygen,  but,  on  the 


GROWTH    OF    PLANTS.  119 

contrary,  return  a  portion  of  the  carbonic  acid 
into  the  atmosphere.  Carbonic  acid  gas  is 
deleterious  both  to  man  and  animals,  and 
hence  it  is  that  plants  in  our  apartments,  if 
placed  in  the  full  light,  are  healthful,  but  are 
likely  to  prove  injurious  at  night. 

The  carbon  thus  derived  from  the  atmosphere 
enters  into  the  composition  of  plants,  and  forms 
their  solid  parts  ;  they  also  imbibe  ammonia  from 
the  atmosphere,  the  latter  (which  is  a  compound 
of  nitrogen  and  hydrogen)  appearing  to  be  es- 
sential for  the  perfection  of  the  flowers  and  fruit. 
The  roots  suck  up  both  carbonic  acid  and  am- 
monia, as  well  as  moisture,  from  the  soil ;  from 
whence  they  also  derive  potash,  soda,  lime,  silica 
or  flint,  and  various  other  substances,  which 
give  to  vegetables  their  hardness.  Thus,  to  bring 
wheat  to  perfection,  it  requires  a  supply  of 
moisture  and  carbonic  acid  to  promote  the 
growth  of  the  blade  ;  silica  to  give  the  culm  or 
stem  its  hardness  and  firmness ;  and  ammonia 
or  nitrogen  for  the  nourishment  of  the  grain  ; 
and,  above  all,  the  sun's  rays  to  give  energy  to 
the  whole,  for  wheat  will  not  succeed  in  regions 
where  the  mean  summer  temperature  is  below 
57°  or  58°. 

Intertropical  America  is  no  less  distinguished 
for  the  splendor  and  luxuriance  of  its  vegetable 


120  DISTRIBUTION    OF    PLANTS. 

productions  than  for  their  variety,  the  number  of 
plants  which  are  natives  of  that  portion  of  the 
globe  being  more  than  double  that  of  those 
which  are  indigenous  to,  or  natives  of,  Europe. 
The  whole  of  Asia  and  its  islands  possess  a 
smaller  number  than  Europe ;  Oceanica,  in- 
cluding Australia,  New  Zealand,  and  the  islands 
in  the  Pacific  Ocean,  less  than  Asia ;  and  Africa 
(as  far  as  hitherto  explored)  a  smaller  number 
than  any  other  portion  of  the  globe  of  similar 
extent. 

Some  species  of  plants  are  met  with  only  in 
very  limited  districts,  to  which  they  appeared  to 
be  wholly  confined ;  thus  the  Irish  yew  appears 
to  grow  naturally  nowhere  except  in  Ireland. 
Other  plants  have  a  much  wider  range ;  thus 
the  Scotch  fir  is  met  with  not  only  in  Scotland, 
but  in  various  other  regions  possessing  a  nearly 
similar  climate.  It  however  appears  that,  gen- 
erally speaking,  particular  kinds  of  plants  form 
the  prevailing'  vegetation  in  certain  portions  of 
the  earth's  surface,  and,  accordingly,  botanists 
have  attempted  to  divide  it  into  botanical  re- 
gions, each  region  being  named  from  the  prepon- 
derance of  certain  plants.  Thus  the  southern 
portion  of  the  United  States  is  called  the  Region 
of  Magnolias,  because  that  plant  grows  in  re- 
markable abundance  and  to  a  splendid  size  in 


DISTRIBUTION    OF    PLANTS.  121 

those  regions.  The  lowlands  of  Mexico  and  of 
some  adjacent  countries  are  called  the  Region 
of  Cacti,  from  the  preponderance  in  those  dis- 
tricts of  the  cactus  tribe  of  plants. 

We  have  seen  that  a  similarity  exists  between 
the  temperature  of  land  near  the  level  of  the  sea 
in  high  northerly  and  southerly  latitudes  and  that 
of  elevated  mountains  in  hot  climates.  We  also 
find  that  a  remarkable  correspondence  occurs 
between  the  plants  which  are  natives  of  regions 
bordering  on  perpetual  snow  (and,  therefore, 
possessing  nearly  similar  climates)  however  re- 
mote they  may  be  from  each  other,  or  however 
different  may  be  their  elevation  above  the  level 
of  the  sea.  The  temperature  of  the  middle  re- 
gion of  mountains  in  equatorial  regions  usually 
approaches  that  of  temperate  zones,  and  the 
plants  growing  in  those  respective  regions  usu- 
ally bear  much  resemblance,  though  they  by  no 
means  exhibit  so  great  a  similarity  as  those  of 
frigid  regions.  The  flora,  or  assemblage  of 
plants,  in  equatorial  regions,  may  be  considered 
as  peculiar  to  those  portions  of  the  globe. 

Baron  de  Humboldt  divides  the  surface  of  the 
earth  into  eight  zones  of  vegetation,  which  are 
named  from  the  prevailing  plants  of  each  zone 
or  region. 

1.  The  equatorial  zone,  or  region  of  palms  and 


122 


DISTRIBUTION    OF    PLANTS. 


bananas,  which  extends  to  about  15°  on  each  side 
of  the  equator,  and  corresponds  to  about  3000 
feet  above  the  level  of  the  sea  under  the  equator. 
The  vegetation  in  this  region  consists  of  dense 
forests,  which  never  lose  their  foliage,  and  to 
which  the  preponderance  of  palm  trees  imparts 
a  peculiar  character.  The  luxuriant  and  lofty- 
trees  are  interlaced  and  overtopped  by  gigantic 
creeping  plants,  or  covered  with  singularly- 
formed  orchidaceous  plants,  which  derive  their 
sustenance  from  the  atmosphere. 

2.  The  tropical  zone,  or  regions  of  tree-ferns 
and  figs,  extending  from  about  latitude  15°  to 
the  tropics.  Tree-ferns  do  not  arrive  at  their 
greatest  perfection  at  the  level  of  the  sea  under  the 
equator,  their  range  being  from  about  1300  feet 
to  5000  feet  above  the  level  of  the  sea.  In  the 
South  Pacific  Ocean,  owing  to  the  more  equable 
climate  of  that  portion  of  the  globe,  tree-ferns 
succeed  in  much  higher  latitudes,  these  trees 
being  very  prevalent  in  the  forests  of  New 
Zealand. 

3.  The  sub4ropical  zone,  or  region  of  laurels 
and  myrtles :  from  the  tropics  to  about  34°. 

4.  The  warm  temperate  zone,  or  region  of  ever- 
green trees :  from  34°  to  45°. 

5.  The  cold  temperate  zone,  or  region  of  de- 
ciduous trees :  from  45°  to  58°. 


DISTRIBUTION    OF    PLANTS.  123 

6.  The  subarctic  zone,  or  region  of  pines  :  from 
58°  to  the  arctic  circle. 

7.  The  arctic  zone,  or  region  of  andromedas 
and  alpine  rhododendrons :  from  the  arctic  circle 
to  72°. 

8.  The  polar  zone,  or  region  of  alpine  plants 
(gentian,  ranunculus,  &c.)  :  from  72°  to  the  far- 
thest limits  of  vegetation.  In  this  region  lichens 
and  mosses  are  very  numerous.  Alpine  plants 
grow  under  the  equator  to  the  elevation  of 
12,000  or  13,000  feet  above  the  level  of  the  sea. 
Owing  to  local  peculiarities,  some  species  grow 
at  still  greater  elevations  in  the  Himalaya  moun- 
tains, springing  up  as  the  snow  melts,  at  the 
height  of  more  than  16,000  feet. 

In  the  temperate  climate  of  Europe  the  ef- 
fects produced  by  elevation  above  the  sea  level, 
though  less  striking  than  in  equatorial  regions, 
are  nevertheless  of  great  importance.  Thus,  in 
the  lowlands  of  Italy  and  Sicily,  and  the  south  of 
Spain,  palms  and  other  plants  of  the  warm  re- 
gions of  the  earth  come  to  perfection  ;  these  are 
succeeded  by  the  orange,  the  fig,  and  the  olive  ; 
the  two  latter  of  which  thrive  in  the  southern 
valleys  of  Switzerland,  but  do  not  succeed  be- 
yond 1000  feet  above  the  level  of  the  sea.  In 
the  latter  region,  the  vine  may  be  successfully 
cultivated   to   the  elevation  of  1600   feet ;  the 


124 


DISTRIBUTION    OF    PLANTS. 


walnut  to  2400  feet ;  and  the  chestnut  to  nearly 
3000  feet.  The  range  of  the  oak,  ash,  and  ma- 
ple, extends  to  about  3800  feet ;  that  of  the  larch 
to  about  6000  feet ;  of  the  pine  to  6800  feet ;  and 
of  the  spruce  fir  to  7400  feet,  which  is  about 
2000  feet  below  the  snow-line  in  that  region. 
Beyond  the  region  of  trees,  heath  and  furze,  in- 
terspersed with  some  low  shrubs,  form  the  prin- 
cipal occupants  of  the  soil,  though  abundance  of 
valuable  alpine  grass  is  met  with  in  some  parts. 
At  still  greater  elevations,  lichens  and  mosses 
grow  in  the  crevices  of  the  otherwise  bare  rocks ; 
and,  even  beyond  the  line  of  perpetual  congela- 
tion, the  singular  vegetable  production  called 
the  palmella  nivalis,  or  red  snow,  which  occurs 
abundantly  in  the  arctic  regions,  is  occasionally 
found  amid  the  perpetual  snow  of  Mont  Blanc. 

An  acquaintance  with  the  various  zones  and 
elevations  above  the  sea-level,  at  which  plants 
of  utility  to  man  will  succeed,  is  of  extreme 
importance  to  all  settlers  in  newly-colonized 
countries ;  for,  as  it  would  be  a  vain  attempt 
to  introduce  into  England  plants  adapted  to 
flourish  only  in  hot  climates,  so  would  it  lead  to 
disappointment  were  we  to  cultivate  in  inter- 
tropical regions  such  as  will  only  thrive  in  tem- 
perate zones,  in  cold  regions  such  as  require  a 
high    summer  temperature,  or   in   dry   regions 


DISTRIBUTION    OF    PLANTS.  125 

such  as  require  abundance  of  moisture.  Now, 
wheat  will  not  succeed  at  or  near  the  level  of  the 
sea  in  intertropical  regions,  nor  will  it  come  to 
perfection  in  climates  where  the  summer  tem- 
perature is  below  57°  Fahrenheit.  It,  however, 
may  be  cultivated  with  great  success,  even  un- 
der the  equator,  between  the  elevations  of  4500 
and  10,000  feet  above  the  level  of  the  sea.  Its 
northern  or  polar  limits  in  North  America  have 
scarcely  yet  been  determined  ;  its  successful  cul- 
tivation does  not  extend  beyond  N.  lat.  58°  in 
the  British  Isles,  but  reaches  to  lat.  64°  in  Nor- 
way, though  in  Sweden  not  beyond  62°,  and  in 
Russia  not  much  beyond  N.  lat.  60°.  The  suc- 
cessful cultivation  of  oats  extends  to  the  north- 
ern extremity  of  the  British  Isles,  and  that  of 
barley  to  Faroe  Isles. 

The  great  practical  utility  of  this  department 
of  Physical  Geography  will  be  evident  to  all ;  it 
will  also  be  readily  conceived  that  a  further 
pursuit  of  the  subject  must  lead  to  great  gratifi- 
cation. And  in  truth,  the  more  our  attention  is 
directed  to  it,  the  more  shall  we  be  convinced 
that  "  The  Lord  God  has  made  to  grow  every 
tree  that  is  pleasant  to  the  sight,  and  good  for 
food." 


126  DISTRIBUTION    OF    ANIMALS. 


XIII.  GEOGRAPHICAL  DISTRIBUTION  OF  ANIMALS. 

The  distribution  of  animals  over  the  surface 
of  the  globe  is,  like  that  of  plants,  greatly  influ- 
enced by  climate  and  temperature.  Animals 
also,  like  plants,  belong  to  particular  regions,  or 
have  their  natural  stations  and  habitations,  though, 
since  a  considerable  number  of  animals  possess 
the  power  of  transporting  themselves  from  one 
region  to  another,  these  cannot  in  all  cases  be  so 
deter minately  fixed. 

The  animal  kingdom  has  been  arranged  in  four 
great  departments  :  I.  Vertebrata,  or  vertebrated 
animals  ;  II.  Articulata,  or  articulated  animals ; 
III.  Mollusca,  or  molluscous  animals ;  and  IV. 
Radiata,  or  radiated  animals. 

The  vertebrated  animals  are  so  named  from 
the  bones  of  the  neck,  which  are  called  vertebra;. 
Animals  belonging  to  this  department  all  possess 
a  skull  and  a  back  bone ;  they  have  organs  of 
sight,  hearing,  smell,  and  taste ;  and  have  never 
more  than  four  limbs,  though  in  some  classes  of 
animals  these  limbs  are  not  so  perfectly  devel- 
oped as  in  others.  This  division  includes  man, 
quadrupeds,  birds,  serpents,  frogs,  tortoises,  croco- 


CLASSIFICATION    OF    ANIMALS.  127 

diles,  and  such  fish  as  cod,  herrings,  &c,  all  of 
which  have  a  bony  skeleton. 

This  department  of  the  animal  kingdom  is 
divided  into  four  classes :  1,  mammalia,  or  animals 
which  suckle  their  young,  such  as  man,  the  cow, 
bat,  whale,  &c. ;  2,  birds ;  3,  reptiles,  such  as 
serpents,  turtles,  frogs,  the  crocodile,  &c. ;  4,  fish, 
that  is,  such  fish  as  possess  a  bony  skeleton. 

The  articulated  animals  are  so  named  from 
artiaihis,  "  a  little  joint,"  on  account  of  their  pe- 
culiar formation,  which  consists  of  a  head  and 
successive  portions  jointed  together.  To  this 
division  belong  the  insect  tribes,  the  earthworm, 
crustaceous  animals  or  Crustacea  (such  as  lob- 
sters, crabs,  shrimps,  &c).  Some  articulated 
animals  have  jointed  limbs  attached  to  the  side 
of  the  body,  like  the  fly,  centiped,  lobster,  &c. 

The  molluscous  animals  are  so  named  from 
mollis,  "  soft,"  because  their  bodies  are  soft  and 
are  without  a  bony  skeleton.  Many  molluscs 
have  shells  forming  a  covering  and  defence  for 
their  soft  bodies ;  the  oyster,  snail,  &c,  possess 
these  protecting  shells :  others  are  destitute  of 
this  covering ;  of  this  we  find  instances  in  the 
common  garden  slug;  the  cuttle-fish,  &c. 

The  radiated  animals  form  the  fourth  great 
division  of  the  animal  world.  They  are  called 
radiated,  because  in  the  greater  number  of  the 


128  DISTRIBUTION    OF    ANIMALS. 

animals  belonging  to  this  division,  the  organs  of 
motion  and  sense  are  considered  to  radiate  from 
a  common  centre,  like  the  petals  or  flower-leaves 
of  a  daisy  or  anemone.  To  this  division  belong 
the  coral  animal,  the  sea-anemone,  &c.  Animals 
of  this  division  are  also  termed  zoophytes,  from 
zo-on,  "  animal,"  and  phi/ton,  "  a  plant,"  because, 
though  in  fact  they  are  living  creatures,  they 
sometimes  bear  a  great  resemblance  to  plants 
in  their  structure. 

When  animals  are  identical  in  their  anatomi- 
cal structure,  they  are  considered  to  belong  to 
the  same  species.  When  two  or  more  kinds  of 
animals  are  very  nearly  alike  in  their  structure, 
though  with  some  differences,  they  are  consid- 
ered to  belong  to  the  same  genus  (plural  genera). 
When  the  differences  are  greater,  they  are  ar- 
ranged into  a  group,  called  an  order.  And 
when  only  a  few  points  of  resemblance  can 
be  traced,  they  are  regarded  as  belonging  to 
the  same  class.  A  department  contains  several 
classes.  Thus,  the  dog  belongs  to  the  depart- 
ment vertebrata,  to  the  class  mammalia,  to 
the  order  carnivora,  to  the  genus  can  is,  and  to 
the  species  dog.  Different  systems  of  classifica- 
tion vary  the  names  of  the  orders  of  mammalia. 
One  system  gives  three  orders,  the  carnivora, 
herbivora,  cetacea;  another  gives   as  many  as 


DISTRIBUTION    OF    ANIMALS.  129 

twelve.  Among  some  species,  we  also  meet 
with  varieties  ;  thus  the  varieties  of  the  dog  are 
the  mastiff,  greyhound,  terrier,  &c. 

The  same  species  of  animals  are  not  met  with 
in  all  parts  of  the  world,  and  even  some  genera 
are  found  to  be  peculiar  to  particular  regions. 
Thus,  the  royal  lion  is  met  with  only  in  Africa, 
the  Asiatic  lion  being  of  a  different  species  and 
of  a  smaller  size.  The  tiger  is  peculiar  to  Asia 
and  some  of  the  Asiatic  islands ;  the  giraffe  to 
Africa ;  the  elephant  is  found  in  Africa  and  in 
some  parts  of  Asia,  but  the  African  and  Asiatic 
elephants  are  of  different  species. 

The  animals  of  the  Old  World  generally  differ 
in  species  from  those  of  the  New  World.  Thus, 
besides  those  we  have  already  enumerated,  the 
ape  and  baboon,  the  hyaena,  panther,  rhinoceros, 
hippopotamus,  horse,  ass,  camel,  buffalo,  croco- 
dile, python,  &c,  are  all  inhabitants  of  the  Old 
World. 

The  puma  (sometimes  erroneously  called  the 
American  lion),  the  jaguar,  the  sloth,  armadillo, 
bison,  lama,  alligator  or  cayman,  boa  con- 
strictor, rattlesnake,  &c,  are  all  peculiar  to  the 
New  World.     V" 

In  the  most  northerly  parts  of  both  continents 
alone  are  the  same  species  of  animals  found ; 
thus,  the  Polar  bear  and  the  Arctic  fox  inhabit 
9 


130  DISTRIBUTION    OF    ANIMALS. 

the  whole  of  the  icy  regions  extending  from 
Spitzbergen  and  Siberia  to  Arctic  America  ; 
these  animals  being  capable  of  enduring  the 
severe  cold  of  those  high  latitudes,  and  of  trav- 
ersing the  frozen  surface  from  one  continent  to 
the  other. 

The  annals  of  a  country,  taken  collectively, 
constitutes  its  fauna.  That  of  Australia  in- 
cludes some  very  singular  forms.  Among  these 
are  the  various  species  of  opossum  and  kangaroo, 
the  ornithorynchus,  or  duck  bill,  &c.  The  flying 
squirrel,  or  flying  cat,  is  found  in  Australia  and 
some  islands  in  the  Indian  Ocean.  Bats  of  vari- 
ous species  are  met  with  in  almost  all  the  warm 
and  temperate  regions  of  the  earth. 

Birds,  like  other  animals,  have  their  natural 
geographical  limits;  and  though  some  have  a 
very  wide  range,  others  are  confined  to  particular 
regions ;  thus,  the  birds  of  paradise  are  found 
only  in  New  Guinea  and  some  adjacent  islands; 
the  beautiful  sun  birds  are  confined  to  Africa, 
and  the  humming  birds  are  peculiar  to  the  New 
World.  The  powers  of  flight  possessed  by  most 
birds,  and  the  migratory  instinct  which  leads 
some  species  of  birds  to  remove  their  quarters  at 
the  change  of  season,  cause  them  to  possess  a 
very  wide  range,  and  to  enjoy  at  all  times  a 
climate  especially  adapted  to  their  wants. 


DISTRIBUTION    OF    ANIMALS.  131 

In  the  animal  as  well  as  in  the  vegetable  king- 
dom, the  largest  number  of  species  is  met  with 
in  the  warm  regions  of  the  globe,  and  a  gradual 
decrease,  in  the  number  both  of  genera  and  spe- 
cies, takes  place  as  we  recede  from  the  equator. 
It  is  in  intertropical  regions  also,  that  mammife- 
rous  quadrupeds  are  most  remarkable  for  their 
magnitude,  strength,  and  ferocity ;  that  reptiles 
are  larger  and  more  venomous ;  that  birds  are 
decked  with  the  most  splendid  plumage,  and  the 
insect  tribes  distinguished  for  their  size  and  the 
brilliancy  of  their  tints.  These  effects  of  light 
and  heat  appear  to  be  extended  even  to  the  in- 
habitants of  the  ocean ;  sharks  and  some  other 
fish  are  larger  and  more  ferocious  in  the  seas  of 
tropical  regions,  and  some  species  of  fish  are 
adorned  with  gayer  colors,  than  those  of  temper- 
ate zones.  It  is  also  from  the  warm  regions  of 
the  earth,  that  the  greater  number  of  the  most 
beautiful  shells  of  molluscous  animals  are  ob- 
tained, and  there,  likewise,  do  the  coral  animals 
and  other  radiata  occur  in  the  greatest  variety 
and  abundance. 

Animals,  like  plants,  are  adapted  for  the  sta- 
tions or  situations  in  which  Creative  Wisdom 
has  placed  them  ;  and  thus  we  find  animals  be- 
longing to  cold  climates  provided  with  warm 
furry  coats,  which  would  be  unsuited  for  the 


132  DISTRIBUTION    OF    ANIMALS. 

inhabitants  of  hot  regions.  Sometimes,  when 
animals  of  the  same  species  inhabit  countries 
possessing  different  climates,  the  garb  of  the  one 
will  differ  from  that  of  the  other,  in  accordance 
with  the  difference  of  climate.  Thus,  the  skin  of 
the  stoat  in  England  is  comparatively  thin,  and 
of  a  dull  grayish  brown  color ;  but  in  northern 
Russia  and  Siberia,  the  coat  of  the  animal  is 
transformed  into  a  beautiful  thick  fur,  of  a  clear 
white  in  every  part  except  the  tip  of  the  tail, 
which  is  of  a  deep  black,  affording,  under  this 
form,  the  well  known  fur  called  ermine. 

If  by  accident,  or  the  agency  of  man,  animals 
are  removed  to  places  uncongenial  to  their  na- 
tures, they  either  perish  altogether,  or  some 
change  takes  place  to  fit  them  for  their  new 
abode.  Thus,  the  race  of  sheep  now  inhabiting 
some  of  the  valleys  of  intertropical  South  Amer- 
ica, which  were  originally  transported  from  tem- 
perate European  regions,  possess,  instead  of 
their  warm  woolly  fleeces,  a  coat  of  glossy  hair, 
better  adapted  to  the  heat  of  the  climate  in 
which  they  have  now  become  naturalized.  Thus, 
again,  a  species  of  dormouse,  which  is  a  native 
of  the  warmer  regions  of  the  earth,  does  not  in 
its  natural  habitation,  where  it  can  at  all  seasons 
of  the  year  obtain  abundance  of  food,  become 
torpid,  or  hybernate ;  but  if  removed  to  England, 


DISTRIBUTION    OF    MAN.  133 

where  its  means  of  subsistence  fail  during  the 
winter,  it  acquires  the  habits  of  the  English 
dormouse,  and  passes  that  season  in  a  state  of 
torpidity. 


XIV.  GEOGRAPHICAL  DISTRIBUTION  OF  MAN. 

The  geographical  distribution  of  man  forms  a 
subject  of  totally  different  character  from  any 
that  has  hitherto  engaged  our  attention.  Instead 
of  speaking  of  genera  and  species,  we  have  now 
to  direct  our  inquiries  to  the  diversities  of  lan- 
guage, and  the  varieties  of  form  and  color,  in  the 
human  race,  and  to  the  distribution  over  the 
earth's  surface  of  these  diversities  and  varieties. 

The  number  of  languages  at  present  spoken  in 
the  world,  is  estimated  at  not  much  less  than 
2000 ;  but  many  of  these  appear  to  be  derived 
from  one  common  root  or  origin.  Thus,  the 
Hebrew,  the  Babylonian,  Syrian,  Arabian,  and 
Abyssinian,  are  considered  to  have  one  common 
origin.  They  are  collectively  called  Semitic,  from 
Shem,  the  son  of  Noah,  from  whom  the  nations 
speaking  these  languages  are  supposed  to  have 
descended.    This  is  called  a  family  of  languages. 


134 


DISTRIBUTION    OF    MAN. 


DISTRIBUTION    OF    MAN. 


135 


Another  family  of  languages,  which  is  called 
the  Indo-European,  includes  a  large  number  of 
the  languages  or  idioms  of  Europe  and  Asia. 

1.  The    Sanscrit,  and  all  its  dialects  in  India. 

2.  The  ancient  Zend,  or  Medo-Persic  language, 
and  all  the  idioms  now  spoken  in  Persia  and 
Armenia.  3.  The  Greek  and  Latin  languages. 
4.  The  Sclavonian.  5.  The  Gothic  or  Teutonic, 
6.  The  Celtic. 

The  languages  of  some  nations,  though  not  so 
distinctly  traceable  to  the  same  origin,  are  often 
found  to  bear  a  great  resemblance  to  each  other, 
and  they  are  then  considered  to  belong  to  the 
same  school  or  class  of  languages.  Such  are 
those  termed  monosyllabic,  from  their  consisting 
of  words  of  one  syllable.  To  this  class  belong 
the  languages  of  China,  Thibet,  Siam,  and 
nearly  all  the  Indo-Chinese  countries. 

Another  class  of  languages  is  those  termed 
polysynthetic.  These  consist  of  long  words  of 
many  syllables,  and  very  elaborate  in  their  con- 
struction. To  this  remarkable  class  of  languages 
belong  all  the  numerous  dialects  or  idioms  of 
both  North  and  South  America. 

A  dispersion  and  separation  into  families  and 
tribes  having  taken  place  at  an  early  period  of 
man's  history,  considerable  differences  in  the 
features  and  the  color  of  the  skin  appear  before 


136  DISTRIBUTION    OF    MAN. 

long  to  have  become  hereditary  in  certain  tribes 
or  nations,  probably  occupying  comparatively 
remote  regions  of  the  earth.  These  peculiarities 
having  formed  permanent  distinctions,  natural- 
ists have  attempted  to  class  the  human  species 
into  certain  races  or  varieties,  according  to  the 
color  of  the  skin  and  the  form  of  the  skull. 

The  three  leading  divisions  are  the  Caucasian, 
the  Mongolian,  and  the  Ethiopian  races :  to 
which  may  be  added,  the  Malayan  and  the 
American  races. 

The  Caucasian,  or  White  race,  is  characterized 
by  a  fair  skin,  sometimes  with  color  in  the  cheeks, 
an  oval  face  and  expanded  forehead,  eyes  vary- 
ing from  blue  to  dark  brown  ;  nose  thin  and 
slightly  aquiline  or  straight,  small  mouth,  and  a 
full  and  rounded  chin  ;  soft  hair,  varying  in  color 
from  black  to  light  brown  and  flaxen,  and  wav- 
ing or  slightly  curled. 

The  most  refined  and  civilized  as  well  as  most 
powerful  nations  of  the  earth  have  belonged  to 
the  Caucasian  race ;  and  it  is  in  the  regions  in- 
habited by  this  race,  that  both  the  Semitic  and 
Indo-European  languages  have  prevailed,  and 
do  still  prevail.  The  ancient  and  modern  inhab- 
itants of  the  regions  bordering  on  Mount  Cauca- 
sus, the  higher  castes  of  India,  the  Afghans,  the 
Medes,  Persians,  and  Arabs,  the  inhabitants  of 


DISTRIBUTION    OF    MAN.  137 

Northern  Africa,  and  the .  Jewish  people,  all 
belong  to  this  race.    y< 

In  Europe,  the  Caucasian  race  includes  the 
ancient  Greeks  and  Romans,  and  the  present 
inhabitants  of  Greece,  Italy,  France,  and  other 
nations  which  derive  their  language  and  descent 
from  the  Greeks  and  Romans ;  the  Sclavonians, 
who  occupy  Russia,  Poland,  and  parts  of  Austria 
and  Turkey ;  the  Teutonic  or  Gothic  tribes,  who 
occupy  Norway  and  Sweden,  Denmark,  Holland, 
Germany,  Prussia,  parts  of  Belgium,  Austria  and 
Switzerland,  and  a  large  portion  of  the  British 
Isles  ;  and  the  Celtic  race,  who  inhabit  the  north- 
western districts  of  Scotland,  the  west  of  Ireland, 
Wales,  and  some  parts  of  Cornwall.  This  race, 
intermixed  with  the  descendants  of  the  ancient 
Romans,  is  also  spread  over  Belgium,  France, 
Switzerland,  Italy,  Spain,  and  Portugal. 

We  thus  find  that  the  Caucasian  race  inhabits 
the  whole  of  Europe,  with  the  exception  of  Lap- 
land, Finland,  and  part  of  Hungary ;  a  large 
portion  of  the  south-western  regions  of  Asia ;  the 
northern  part  of  Africa,  from  about  N.  lat.  20° 
to  the  borders  of  the  Mediterranean  Sea;  and 
through  European  colonists,  a  considerable  por- 
tion of  America,  and  of  various  other  regions  of 
the  globe. 

The  Mongolian  race  is  characterized  by  a  yel- 


138 


DISTRIBUTION    OF    MAN. 


lowish  or  olive-colored  skin,  a  broad  and  flat- 
tened face,  with  a  low  and  narrow  forehead ; 
small  black  eyes  obliquely  set,  a  wide  mouth 
and  thick  lips ;  black  hair,  lank  and  thin.  The 
Mongolian  race  at  the  present  day  occupies  a 
large  portion  of  Asia,  to  the  north  and  east  of 
the  Himalaya  Mountains.  The  nomadic  or  wan- 
dering Mongolian  and  Kalmuc  tribes  belong  all 
to  this  race;  as  do  also  the  Chinese,  the  Sa- 
moieds,  and  the  inhabitants  of  Kamschatka. 
This  race  also  occupies  Finland,  Lapland, 
Greenland,  and  part  of  Hungary,  though  in  the 
last  territory  the  characteristic  features  of  the 
Mongolian  race  are  much  less  strongly  marked. 

The  Ethiopian  or  Negro  race  is  characterized 
by  a  black  or  very  dark  skin ;  a  narrow  com- 
pressed skull,  a  low  and  narrow  forehead,  black 
eyes,  a  flat  broad  nose  ;  thick  lips,  especially  the 
upper  lip ;  a  small  chin ;  woolly,  crisp,  coarse  hair, 
collected  into  little  knots.  This  race  is  consid- 
ered to  occupy  nearly  the  whole  of  Africa  to  the 
south  of  the  Great  Desert ;  parts  of  Madagascar, 
Australia,  and  New  Guinea ;  and  some  of  the 
islands  included  in  the  Indian  and  Polynesian 
groups. 

The  Malay  or  Malayan  race  bears  much  re-, 
semblance  to  the  Mongolian,  though  in  the  Ma- 
layan race  the  color  of  the  skin  is  darker,  and  the 


DISTRIBUTION    OF    MAN.  139 

face  less  broad.  This  race  occupies  the  Malay 
Peninsula,  and  a  large  portion  of  the  islands  of 
the  Indian  Archipelago. 

The  American  race  is  characterized  by  a  red- 
dish colored  skin ;  by  a  high  and  receding  fore- 
head, with  generally  regular  features,  and  a 
rather  prominent  and  frequently  aquiline  nose. 
This  race,  though  fast  diminishing  from  the  face 
of  the  earth,  includes  the  aboriginal  inhabitants 
of  the  whole  American  continent.  All  the  tribes 
occupying  that  vast  range  of  country  speak  dia- 
lects or  tongues  allied  to  each  other  and  belong- 
ing to  that  singular  class  which  is  formed  of 
long  polysyllables.  The  number  of  different 
dialects  in  America  is  estimated  at  no  less  than 
1500. 

The  diversities  of  language  on  the  face  of  the 
globe  tend  to  the  disunion  of  man  from  his  fel- 
low man  :  and  undoubtedly  we  must  look  to 
the  spread  of  the  Gospel,  as  the  sole  efficient 
means  of  restoring  union  among  mankind,  and 
of  leading  all  the  different  members  of  the  human 
race  to  feel  that  they  belong  to  one  great  family, 
that  they  are  all  brethren,  and  children  of  one 
Father.  It  may  be  little  that  we  individually 
can  do  to  promote  this  grand  object,  but  we 
may  endeavor  to  perform  our  part.  By  the 
acquirement  of  foreign  languages,  we  may  be 


140  DISTRIBUTION    OF    MAN. 

better  enabled  to  meet  every  man  as  our  brother ; 
and  by  the  exercise  of  kindly  feelings,  and  the 
mutual  interchange  of  good  offices,  not  only 
amongst  our  kindred  and  our  countrymen, 
but  amongst  strangers  and  foreigners  from 
every  part  of  the  globe,  we  may  be  instrumental 
in  promoting  "  peace  on  earth,  good-will  towards 
men." 


141 


EXERCISES  FOR  THE  EXAMINATION  OF  PUPILS. 


I.  The  Objects  op  Physical  Geography,  (p.  1.) 

What  is  meant  by  Physical  Geography  ?  — Why  is  it  called 
Physical  or  Natural  Geography  ?  —  What  advantages  may  result 
from  its  pursuit  ? 

II.   The  Earth,  (p.  2.) 

To  what  group  of  bodies  does  the  earth  belong  ? 

What  is  the  form  of  the  earth  ?  —  Mention  three  different 
modes  by  which  the  rotundity  of  the  earth  may  be  proved. 

How  is  the  earth  or  globe  divided  into  two  parts  ?  —  How  are 
maps  of  the  world  frequently  divided  ? 

What  is  the  circumference  of  the  earth  ?  —  What  is  its  diame- 
ter from  east  to  west  ?  — What  from  north  to  south  4 

Give  some  account  of  the  earth's  turning  on  its  axis  ;  or  of  its 
diurnal  motion.  —  Also  of  its  motion  in  its  orbit.  —  How  is  the 
earth  placed  in  its  orbit  ?  and  what  is  the  consequence  of  this 
position  ?  —  Relate  some  particulars  about  mid-summer  and 
mid-winter. 

III.  Latitude  and  Longitude,  (p.  9.) 

How  is  the  earth  or  globe  divided  for  the  convenience  of  mea- 
surement ?  —  How  i3  latitude  marked  ?  and  how  many  degrees 
of  latitude  are  there  ?  —  From  what  is  latitude  reckoned  ?  — 
What  is  meant  by  high  and  low  latitudes  ?  — How  are  degrees 
subdivided? — How  many  miles  are  there  in  a  degree  of  lati- 


142  EXERCISES    FOR    EXAMINATION. 

tude  ?  —  What  is  meant  when  it  is  said  that  places,  are  on  the 
same  parallel  of  latitude  ? 

How  is  the  earth  divided  by  circles  running  parallel  with  the 
equator  ?  —  Mention  the  zones  into  which  these  divide  the  earth  ; 
also  the  parallels  of  latitude  to  which  they  extend ;  and  for  what 
cause  particular  names  have  been  given  to  these  zones. 

How  is  longitude  determined  ?  and  from  what  is  it  reck- 
oned ?  —  How  many  degrees  of  longitude  are  there  ?  —  Give  some 
particulars  about  the  number  of  miles  contained  in  degrees  of 
longitude  ;  and  their  difference  in  different  latitudes.  —  What  is 
the  length  of  a  degree  of  longitude  on  the  parallel  of  London  ?  — 
Give  the  meaning  of  the  terms  east  and  west  longitude.  —  When 
are  places  said  to  be  on  the  same  meridian  ?  —  What  is  meant 
when  we  speak  of  the  sun's  being  on  the  meridian  ? 

IV.  Distribution  of  Land  and  Water,  (p.  14.) 

What  is  the  estimated  proportion  of  land  to  water  on  the  sur- 
face of  the  globe  ?  —  What  in  the  northern  and  southern  hemi- 
spheres ? 

Under  what  general  heads  may  the  dry  land  be  considered  ?  — 
Give  an  account  of  the  two  great  continents.  —  Why  are  they 
called  the  old  and  new  continents  ? 

Describe  islands.  —  Mention  the  largest  island  on  the  earth's 
surface.  —  What  regions  are  included  under  the  appellation 
of  Ocean  ica  ? 

How  is  the  land  arranged  in  the  eastern,  and  in  the  western 
continent  ?  —  Mention  the  direction  of  the  greatest  extension  of 
land  in  the  two  continents. 

V.  Variations  of  the  Surface,  (p.  17.) 

Describe  the  variations  of  the  earth's  surface.  —  Mention  the 
usual  arrangement  of  mountains. 

Give  some  account  of  mountain  ranges.  — What  direction  do 
they  usually  appear  to  take  ? 


EXERCISES    FOR    EXAMINATION.  143 

Give  the  names  of  the  principal  mountain  ranges  which  extend 
across  the  old  continent.  —  Give  the  names  of  the  mountain 
ranges  which  extend  from  north  to  south  in  the  new  continent. 

How  are  mountain  ranges  frequently  disposed,  in  peninsulas 
and  islands  ? 

Give  some  particulars  about  the  appearance  and  form  of  moun- 
tains, and  about  glaciers. — Describe  mountain  branches,  and 
spurs.  —  What  are  detached  or  isolated  mountains  ?  —Where  are 
the  loftiest  summits  usually  met  with  ?  —  Give  the  heights  of  the 
principal  mountains. 

Describe  table-lands,  or  plateaus.  —  Mention  the  most  remark- 
able plateau  or  table-land  in  Europe. —  Mention  table-lands  in 
Mexico,  in  the  Andes,  and  in  Asia. 

Describe  plains  or  lowlands.  —  Mention  the  most  remarkable 
in  Europe  ;  in  Asia  ;  and  in  Africa.  —  Describe  the  lowlands  of 
North  and  of  South  America  ;  and  mention  by  what  names  they 
are  distinguished. 

What  are  the  various  kinds  of  valleys  ?  —  Describe  principal 
valleys ;  lateral  or  transverse  valleys ;  and  subordinate  valleys.  — 
Describe  basin-shaped  valleys.  —  Give  the  various  terms  applied 
to  narrow  valleys  ;  and  for  what  cause  some  of  these  terms  have 
been  applied. 

What  forms  the  standard  by  which  all  the  undulations  of  the 
earths  sui-face  are  measured  ? 


VI.  Geology,  (p.  33.) 

What  is  Geology  ?  —  What  is  meant  by  the  earth's  crust  ?  — 
Of  what  does  the  earth's  crust  consist  ?  —  Mention  the  various 
kinds  of  rocks.  —  State  also  the  meaning  of  the  term  fossil ;  and 
give  some  particulars  about  the  general  diffusion  of  fossils  in  all 
parts  of  the  earth's  crust. 

Describe  earthy  formations  ;  also  pebbles,  gravels,  shingles, 
and  boulders. — What  is  conglomerate,  or  pudding-stone?  — 
What  is  breccia  ? 


144  EXERCISES    FOR    EXAMINATION. 

Mention  the  most  abundant  earths.  —  In  what  mineral  sub- 
stance is  silex  found  in  a  pure  state  ?  —  In  what  form  is  lime 
usually  met  with  ?  —  What  useful  property  does  clay  possess  ? 

How  are  rocks  classed  ?  —  What  are  stratified  or  sedimentary 
rocks  ?  —  How  do  they  seem  to  have  been  formed  ?  —  How  are 
stratified  rocks  arranged  ?  and  how  is  their  relative  age  de- 
termined ? 

By  what  means  are  the  lower  rocks  sometimes  brought  to  the 
surface  ?  —  Give  the  meaning  of  the  term  "  crop  out."  —  Men- 
tion the  advantages  which  may  result  from  this. 

What  are  unstratified  rocks  ?  —  Mention  the  apparent  mode 
of  their  formation ;  and  name  the  principal  rocks  of  this  kind. 

Into  what  three  classes  are  unstratified  rocks  divided  ?  —  De- 
scribe plutonic  rocks.  —  State  under  what  circumstances  they 
are  supposed  to  have  become  consolidated.  —  Describe  trap  rocks. 

—  Mention  the  principal  rocks  of  this  class.  —  Describe  volcanic 
rocks.  — Mention  the  principal  products  of  active  volcanoes. 

In  what  regions  of  the  earth  do  the  most  remarkable  active 
volcanoes  occur  ?  —  How  may  volcanic  eruptions  prove  beneficial  ? 

—  Give  some  account  of  a  tremendous  eruption  in  Iceland. — 
State  the  apparent  connection  between  earthquakes  and  volcanic 
eruptions. 

WThat  effects  are  sometimes  produced  by  earthquakes? — Do 
earthquakes  occur  in  regions  remote  from  active  -volcanoes  ? 

Give  some  account  of  extinct  volcanoes.  —  Describe  intrusive 
rocks,  and  metamorphic  rocks.  —  Give  an  instance  of  a  trans- 
formed rock? 

What  are  dislocations  or  faults  ?  —  What  benefit  results  from 
faults  ?  — What  do  fissures  sometimes  contain  ? 

Give  some  particulars  about  metallic  veins.  —  Where  is  gold 
usually  found  ?  —  Where  are  copper,  tin,  lead,  silver,  and  iron 
usually  found  ? 


EXERCISES    FOR    EXAMINATION.  145 


VII.  The  Waters  of  the  Globe,  (p.  45.) 

Under  what  heads  may  the  waters  of  the  globe  be  considered  ? 

From  what  do  springs  take  their  rise?  —  How  are  internal 
reservoirs  supplied  with  water  ?  — What  does  spring  water  con- 
tain ?  and  what  forms  the  distinction  between  soft  water,  hard 
water,  and  mineral  water  ? 

How  may  mineral  springs  be  classed  ?  —  Describe  acidulous 
springs.  —  Describe  chalybeate  springs.  —  Describe  sulphureous 
springs.  —  Describe  the  two  kinds  of  saline  springs;  — Describe 
calcareous  springs  ;  and  give  some  account  of  their  mineralizing 
or  petrifying  properties.  —  Describe  stalactites  and  stalagmites. 
— Describe  siliceous  springs. 

Are  thermal  or  hot  springs  of  frequent  occurrence  ?  —  Describe 
the  two  kinds  of  hot  springs.  —  Give  some  particulars  about  the 
temperature  of  the  earth  at  various  depths ;  and  mention  by  what 
means  this  has  been  ascertained. — Which  kind  of  springs  has 
usually  the  highest  temperature  ?  —  Name  some  remarkable  hot 
springs.  —  Describe  bituminous  springs. 

From  whence  do  rivers  derive  their  supplies  of  water  ?  —  What 
is  meant  by  the  term  water-shed  ?  — What  constitutes  the  basin 
of  a  river  ?  —  Give  the  area  of  the  principal  river-basins. 

On  what  does  the  velocity  of  a  river  in  great  measure  depend  ? 
—  Describe  cataracts,  cascades,  and  rapids.  —  Describe  deltas  ; 
and  estuaries. — What  is  meant  by  the  bore? — Give  some 
particulars  about  flood-seasons,  or  freshets.  — What  is  the  num- 
ber of  considerable  rivers  in  the  Old  World  ?  —  What  in  the 
New  ?  —  Give  the  length,  situation,  and  termination  of  the  prin- 
cipal rivers. 

Give  some  account  of  the  various  kinds  of  lakes.  — Describe 
lakes  at  the  sources  of  springs  ;  lakes  in  the  course  of  a  river  ; 
lakes  in  depressions  of  the  earth  j  lakes  in  the  craters  of  extinct 
volcanoes  ;  periodic  lakes.  —  Mention  the  largest  lake  in  Eng- 
land j  the  largest  lakes  in  Europe  ;  in  Asia  ;  in  North  America. 

What  advantages  result  from  the  great  extent  of  the  ocean  ? 
10 


146  EXERCISES    FOR    EXAMINATION. 

—  Does  the  ocean  form  one  vast  mass  of  waters  ?  —  Give  its  geo- 
graphical divisions.  —  Describe  branch  or  inland  seas.  —  De- 
scribe lochs,  voes,  and  fiords. 

Give  some  particulars  about  the  depth  of  the  ocean  ;  about  its 
temperature  ;  about  its  saline  contents.  —  Mention  the  usual 
degree  of  saltness  of  inland  seas  ;  and  what  sea  forms  an  excep- 
tion to  the  general  rule. 

What  is  the  freezing  point  of  sea-water  ?  —  Give  some  account 
of  icebergs. 

Does  it  appear  that  sea-water  has  any  color  ?  —  Is  its  color 
sometimes  influenced  by  its  bed  ?  —  Also  by  the  presence  of 
minute  animals  ?  —  What  causes  the  luminous  appearance  of  the 
ocean  ? 

VIII.  Tides,  Waves,  and  Currents,  (p.  68.) 

What  causes  the  perpetual  movement  of  the  waters  of  the 
ocean  ?  —  By  what  attraction  are  the  waters  retained  in  their 
bed  on  the  earth's  surface? — By  what  attraction  is  the  great 
primary  or  tidal  wave  formed  ?  —  How  is  ebb-tide  or  low  water 
on  our  shores  produced  ?  —  How  is  flood-tide  or  high  water  pro- 
duced ?  — What  are  spring  tides  ?  —  State  the  course  of  the  At- 
lantic tidal  wave ;  and  the  difference  between  high  and  low 
water  at  various  places. 

Describe  secondary  or  wind  waves.  —  Describe  the  ground 
sea. 

What  causes  the  currents  of  the  ocean  ?  —  And  which  are  the 
most  remarkable  currents  ?  —  Describe  the  polar  currents.  — 
Also  the  equatorial  currents.  —  And  the  great  system  of  cur- 
rents commencing  in  the  Antarctic  Seas.  —  Describe  the  Gulf 
Stream. 

IX.  The  Atmosphere,  (p.  75.) 

Describe  the  earth's  atmosphere  ;  and  mention  its  height.  — 
Of  what  is  atmospheric  air  composed  ?  —  Give  some  account  of 


EXERCISES    FOR    EXAMINATION.  147 

the  elasticity  and  the  density  of  air.  —  Mention  the  consequences 
to  which  these  gives  rise.  —  State  what  is  meant  by  the  term 
"  weight  of  an  atmosphere ; ' '  and  give  some  particulars  about 
the  barometer. 

What  effects  are  produced  on  the  temperature  of  the  air  by 
height  above  the  sea-level  ? 

What  appears  to  give  rise  to  winds  ?  —  Give  some  particulars 
about  winds.  —  Give  an  account  of  the  trade-winds. — What 
causes  south-westerly  and  north-westerly  winds  to  prevail  in 
higher  latitudes  ?  —  Give  a  description  of  monsoons.  —  What 
causes  sea-breezes,  and  land-breezes  ? 

What  are  hurricanes  ?  and  what  are  typhoons  and  ox-eyes  ?  — 
How  do  tornadoes,  pamperas,  and  arched  squalls  differ  from  hur- 
ricanes ? 

Describe  the  sirocco,  solano,  simun  or  simoon,  and  also  the 
harmattan. 

In  what  state  is  water  always  present  in  the  atmosphere  ?  and 
by  what  means  does  it  find  its  way  there  ?  —  How  is  dew  formed  ? 
and  when  is  it  most  abundantly  deposited  ?  —  On  what  substance 
is  dew  usually  most  copiously  deposited  ? 

When  are  mists  and  fogs  likely  to  be  formed  ? 

How  are  clouds  formed  ?  and  of  what  do  they  consist  ?  —  Men- 
tion also  how  rain  is  formed,  and  under  what  circumstances  hail 
and  snow  are  formed. 

What  names  are  given  to  the  principal  forms  of  clouds  ?  —  De- 
scribe the  four  principal  kinds  of  clouds.  —  At  what  height  in 
the  atmosphere  is  the  zone  of  clouds  ?  and  which  are  the  highest, 
and  which  the  lowest  clouds  ?  —  Mention  the  names  of  the  com- 
binations of  the  principal  kinds  of  clouds. 

-In  what  parts  of  the  earth  does  the  largest  quantity  of  rain 
fall  ?  —  Is  it  more  abundant  in  the  New  than  in  the  Old  World  ? 
Mention  the  rainless  districts  of  the  earth.  —  State  the  cause  of 

the  difference  in  the  amount  of  rain  in  different  regions What 

difference  is  there  in  the  quantity  of  rain  in  the  eastern  and 
western  parts  of  the  British  Isles  ? 


148  EXERCISES    FOR    EXAMINATION. 

Give  some  particulars  about  rainy  and  dry  seasons;  and  also 
relativeto  the  belt  or  zone  called  the  "variables." — Give  an 
account  of  the  fall  of  rain  in  intertropical  countries,  and  in 
countries  beyond  the  tropics. 

X.  Climate,  (p.  95.) 

What  is  meant  by  the  term  climate  ?  —  What  are  the  most 
prominent  causes  of  diversity  of  climate  ? 

What  is  the  grand  agent  in  diffusing  heat  over  the  earth's 
surface  ?  —  Mention  the  effects  produced  by  the  earth's  diurnal 
rotation ;  and  also  the  beneficial  results  from  its  inclined  position 
in  its  orbit. 

How  far  does  the  artificial  division  of  the  earth  into  torrid, 
frigid,  and  temperate  zones  correspond  with  the  climates  of 
those  regions  ? 

Mention  another  leading  cause  of  the  diversity  of  climate  ?  — 
What  is  signified  when  we  speak  of  an  insular  climate  ?  —  What 
by  an  excessive  climate  ?  —  Mention  an  instance  of  the  effects 
produced  by  a  large  surface  of  water  in  tempering  or  moderating 
the  climate  of  some  regions  of  the  earth. 

Mention  another  leading  cause  of  the  diversity  of  climate  ;  and 
give  an  account  of  the  height  of  the  snow-line  in  different  re- 
gions. —  Refer  to  the  tabular  view  for  its  height  in  various  lati- 
tudes.—  What  appears  to  be  the  cause  of  its  greater  height  at 
certain  distances  from  the  equator,  than  under  that  line  ?  — 
Mention  the  beneficial  results  arising  from  the  different  tempera- 
ture at  different  heights.  —  Describe  the  effects  produced  on 
vegetation  by  elevation  above  the  sea-level,  in  the  hot  regions  of 
the  earth. 

Give  some  account  of  the  temperature  of  mountains  near 
table-lands.  —  Mention  the  Himalaya  Mountains  as  an  example; 
and  state  some  particulars  about  isolated  mountains  in  different 
climates. 

What  effects  are  produced  on  climate  by  the  nature  of  the  soil  ? 


EXERCISES    FOR   EXAMINATION.  149 

— What  by  the  prevailing  winds?  —  How  do  mountain  ranges 
affect  climate  ?  —  What  effects  are  produced  by  the  currents  of 
the  ocean  ?  —  Give  some  account  of  the  Sea  of  Sargasso  ;  and 
mention  the  effects  it  produces  on  the  temperature  of  the  North- 
ern Ocean. 

What  districts  usually  possess  more  excessive  climates  ?  — 
Does  the  temperature  vary  as  much  in  intertropical,  as  in  tem- 
perate regions  ? 

What  are  isothermal  lines  ? — Do  they  run  parallel  with  the 
equator  ?  —  What  are  isotheral  and  isochimenal  lines  ?  —  What 
is  the  average  degree  of  heat  of  the  line  of  highest  temperature ; 
—  What  regions  does  it  cross  ? — Which  is  considered  to  form 
the  hottest  region  of  the  earth  ? 

XT.  Electricity  and  Magnetism,  (p.  109.) 

Does  Electricity  act  any  part  in  the  natural  world  ?  —  Mention 
what  is  meant  by  ordinary  electricity,  and  how  it  may  be  called 
forth,  and  what  is  meant  by  voltaic  electricity. 

What  is  meant  when  it  is  said  that  any  substance  is  positively 
electrified  ?  and  what  when  negatively  electrified  ?  —  Give  some 
particulars  about  the  electrical  state  of  substances,  and  of  the 
effects  produced  if  they  come  in  contact. 

In  what  state  of  electricity  is  the  earth  considered  always  to 
be;  and  in  what  pure  atmospheric  air? — Mention,  also,  by 
what  means  the  electrical  equilibrium  of  the  air  is  liable  to  be 
disturbed,  and  how  it  is  sometimes  restored.  —  At  what  periods 
of  the  day  and  of  the  year  is  electrical  intensity  greatest  ? 

What  effects  does  it  appear  that  voltaic  electricity  is  continu- 
ally producing  in  the  earth's  crust  ?  and  what  substances  are 
supposed  to  be  formed  by  its  powerful  agency  ? 

What  is  terrestrial  magnetism  ?  —  Under  what  heads  may  it 
be  considered  ?  —  How  may  the  magnetic,  or  attractive  power  of 
the  loadstone  be  imparted  to  iron  or  steel,  or  how  may  it  become 
magnetized  ?  —  What  is  meant  by  the  magnetic  direction  of  the 
compass  needle  ?  —  In  what  direction  does  the  needle  point  ?  — 


150  EXERCISES    FOR    EXAMINATION. 

Is  this  subject  to  variation,  and  what  is  the  variation  termed  ?  — 
What  is  meant  by  lines  of  eastward  and  westward  variation  ?  — 
What  by  lines  of  no  variation  ? 

What  is  meant  when  we  speak  of  the  dip  or  inclination  of  the 
magnetic  needle  ?  —  Describe  the  magnetic  equator. 

XII.  Geographical  Distribution  of  Plants,  (p.  114.) 

Give  some  particulars  about  the  plants  on  the  earth's  surface  ? 
Mention  the  adaptation  of  plants  to  all  parts  of  the  earth. 

Into  what  classes  are  plants  naturally  divided  ? 

Describe  cryptogamic,  or  a-cotyledonous  plants.  —  Describe 
endogenous,  or  mono-cotyledonous  plants.  —  Describe  exogenous, 
or  di-cotyledonous  plants. 

Which  class  of  plants  includes  the  greatest  number  of  species  ? 
—  What  is  the  proportion  of  the  different  classes  in  different 
zones  ? 

Describe  perennial  annual,  and  biennial  plants. — Describe 
deciduous  plants  ;  and  mention  in  what  parts  of  the  earth  they 
most  abound.  —  Give  an  account  of  the  peculiar  character  of 
the  evergreen  trees  of  hot  regions,  and  that  of  those  of  cold 
regions. 

From  what  do  plants  derive  their  nourishment?  —  What  ef- 
fects are  produced  on  plants  by  light  ?  —  Give  some  particulars 
about  the  composition  of  plants,  and  what  is  required  to  bring 
them  to  perfection. 

In  what  regions  of  the  earth  are  the  "vegetable  productions 
most    varied  ?  —  State  the  relative  proportion  in  the  different 


Are  the  same  plants  met  with  in  all  regions  possessing 
similar  climates?  —  How  is  the  earth  divided  into  botanical 
regions  ? 

Give  some  account  of  the  correspondence  between  the  plants  of 
Arctic  regions  and  those  of  high  mountains  in  hot  climates  ;  also 
of  the  resemblance  between  those  of  temperate  regions  and  of 
the  middle  region  of  such  mountains.  —  Give  Baron  Humboldt's 


EXERCISES    FOR    EXAMINATION.  151 

division  of  the  earth  into  eight  zones.  —  Give  the  scale  of  vege- 
tation at  various  heights  in  temperate  Europe. 

On  what  account  is  it  important  to  be  acquainted  with  the 
zones  and  climates  in  which  plants  will  succeed  ?  —  Mention  the 
highest  northern  limit  of  the  successful  cultivation  of  wheat,  oats, 
and  barley,  in  Europe.  —  State  how  gratifying  the  pursuit  of 
this  science  is  likely  to  prove. 

XIII.  Geographical  Distribution  op  Animals,  (p.  126.) 

Does  it  appear  that  the  distribution  of  animals  on  the  earth's 
surface  is  influenced  by  climate  ? 

Mention  the  four  great  departments  of  the  animal  kingdom. 

Why  are  vertebrated  animals  so  named,  and  what  is  their  pe- 
culiar characteristic  ?  and  what  animals  are  included  in  this 
division  ?  —  Into  what  four  classes  are  vertebrated  animals  sub- 
divided ? 

Why  are  articulated  so  named,  and  what  animals  are  included 
in  this  division  ?  —  State,  also,  what  animals  are  called  crusta- 
ceous. — Why  are  molluscous  animals  so  named,  and  what  ani- 
mals belong  to  this  division  ?  —  Why  are  radiated  animals  so 
named,  and  what  animals  belong  to  this  division  of  the  animal 
kingdom  ? 

Which  of  these  four  divisions  ranks  as  the  lowest  among  living 
creatures  ?  and  which  is  the  highest  ?  —  Which  forms  the  highest 
class  among  vertebrated  animals  ? 

Give  the  meaning  of  the  several  terms  species,  genus,  order, 
class,  and  department ;  and  give  the  example. 

Do  we  find  that  certain  species  of  animals  are  peculiar  to  par- 
ticular regions  ?  —  Mention  some  of  the  animals  peculiar  to  the 
Old  World.  —  Mention  some  animals  peculiar  to  the  New 
World.  —  What  animals  are  met  with  in  the  more  northerly  re- 
gions of  both  continents  ?  —  Mention  the  peculiarity  of  the  group 
of  animals  inhabiting  Australia. 

Give  some  account  of  the  geographical  distribution  of  birds. 


152  EXERCISES    FOR   EXAMINATION. 

Are  the  animals  inhabiting  warm  regions  usually  more  con- 
spicuous than  those  of  temperate  regions  ? 

Give  some  account  of  the  adaptation  of  animals  to  the  regions 
which  form  their  natural  habitations  ;  and  give  instances  of  the 
changes  which  sometimes  take  place  when  animals  are  removed 
to  other  climates. 

XIV.  Geographical  Distribution  of  Man.  (p.  133.) 

How  many  languages  or  dialects  are  now  spoken  in  the  world  ? 
—  What  are  languages  called,  which  appear  to  be  derived  from 
the  same  root  or  origin  ?  —  Why  is  one  family  of  languages  called 
"  Semitic  ?  ''  —  Give  an  account  of  the  Indo-European  family  of 
languages. 

What  are  schools  of  languages,  or  classes  of  languages  ?  — 
What  languages  are  included  in  the  mono-syllabic  class  ?  — 
What  languages  are  included  under  the  class  called  poly-syn- 
thetic ? 

To  what  consequences  did  the  dispersion  of  mankind  appa- 
rently lead  ?  —  Mention  the  leading  divisions  or  varieties  of  the 
human  race. 

What  are  the  characteristics  of  the  Caucasian  race  ?  —  What 
regions  have  they  occupied,  and  at  present  still  occupy  ?  —  WThat 
are  the  characteristics  of  the  Mongolian  race,  and  what  regions 
do  they  occupy  ?  —  What  are  the  characteristics  of  the  Ethiopian 
or  Negro  race,  and  what  regions  do  they  occupy  ?  —  What  are 
the  characteristics  of  the  Malay  or  Malayan  race,  and  what  re- 
gions do  they  occupy  ?  —  What  are  the  characteristics  of  the 
American  race,  and  what  portion  of  the  globe  do  they  occupy  ? 

What  has  tended  to  disunite  mankind,  and  what  may  tend  to 
restore  union  among  the  human  race  ? 


153 


QUESTIONS  FOR  INVESTIGATION. 

TO    THE    TEACHER. 

After  closing  the  study  of  this  book,  it  will 
be  well  to  enter  upon  these  questions,  which  are 
intended  to  call  into  action  the  reason  of  the  pu- 
pil as  well  as  his  memory.  In  many  instances 
it  will  be  necessary  to  direct  the  pupil  to  other 
sources  of  information  than  those  mentioned  in 
the  preface,  and  to  give  oral  instruction  to  the 
class. 


7^ 


What  does  Physical  mean  ? 
What  is  meant  by  commerce  ? 
Can  a  knowledge  of  Physical  Geography  pro- 
mote Commerce  ?     How  ? 

What  does  the  word  diameter  mean  ? 
Has  the  earth  more  than  one  diameter  ? 
Has  it  several  of  the  same  length  ? 
What  does  spheroid  mean  ?   spheroidal  ? 


154  QUESTIONS    FOR    INVESTIGATION. 

How  is  the  earth  supposed  to  have .  obtained 
its  spheroidal  shape  ? 

Suppose  that  a  round  ball  of  putty  were  placed 
on  a  rapidly  revolving  spindle,  would  it  retain  its 
round  shape  ? 

What  shape  would  it  assume  ? 

What  is  meant  by  centrifugal  force  ?  by  cen- 
tripetal force  ? 

Wille  the  centrifugal  force  be  greater  at  the 
equator  or  at  the  pole%?     Why  ? 

Would  a  leaden  bullet  weigh  the  same  at  the 
equator  as  at  the  poles  ? 

Would  a  pendulum  vibrate  with  equal  rapid- 
ity at  the  equator  and  at  the  poles  ? 

Give  the  reason  for  your  answer. 

How  far  is  it  from  the  poles  to  the  centre  of 
the  earth  ? 

What  is  the  most  common  mineral  found  in 
the  earth  ? 

Is  it  commonly  found  pure  ? 

What  town  do  you  think  to  be  at  the  middle 
of  Europe  ?  of  America  ? 

What  is  the  middle  of  the  Eastern  Hemi- 
sphere ?  of  the  Western  ? 

You  may  name  some  benefits  which  result 
from  the  preponderance  of  water  over  land  on 
the  globe. 


QUESTIONS    FOR    INVESTIGATION.  155 

What  is  the  chief  cause  of  the  unevenness  of 
the  land? 

If  the  earth  presented  a  flat  surface,  what 
would  be  the  consequence  ? 

Which  is  the  largest  of  the  oceans  ? 

Does  the  same  climate  always  exist  within  the 
same  zones  ? 

If  North  America  be  considered  as  main  land, 
what  immense  peninsula  extends  from  it  ? 

Name  another  immense  peninsula. 

What  country  seems  to  have  the  most  coast- 
line in  proportion  to  its  size  ?    What  the  least  ? 

What  country  then  has  the  most  numerous 
harbors  ? 

Compare  Asia  with  South  America  in  this 
respect  ? 

Which  way  do  most  large  peninsulas  turn  ? 

Mention  exceptions  ? 

Mention  some  of  the  uses  of  mountains  ? 

What  kind  of  vegetation  would  you  expect  to 
nnda,t  the  summits  of  the  highest  mountains  ? 

Describe  a  glacier. 

How  fast  are  they  supposed  to  move  ?  owE. ,%  +JL.J, 

What  are  avalanches  ? 

Can  you  find  an  account  of  an  avalanche 
among  the  White  Mountains  ?     IfJiU  ^"" 

From  what  do  volcanoes  receive  their  name  \ 

From  what  is  the  crater  called  ? 


156  QUESTIONS    FOR    INVESTIGATION. 

What  does  steppe  mean  ? 

Where  are  steppes  found  ? 

What  important  use  do  deserts  subserve  ? 

How  are  the  lowland  plains  of  North  America 
situated  ? 

Point  out  a  water-shed  in  Europe  ;  in  Asia  ; 
in  Africa  ? 

What  is  a  rolling  prairie  ? 

What  general  shape  have  islands  which  lie 
along  the  coasts  of  continents  ?    Give  examples. 

How  can  you  account  for  this  ? 

Generally  speaking,  are  the  largest  islands 
found  near  to,  or  remote  from,  the  shore  ? 

What  exceptions  can  you  name  ? 

What  are  volcanic  islands  ? 

Give  examples  of  them  ? 

Are  volcanic  islands  always  permanent  ? 

Can  you  find  any  instance  of  the  disappear- 
ance of  volcanic  islands  ? 

How  are  coral  rocks  formed  ? 

What  are  Atolls  ? 

What  are  the  principal  causes  of  change  in  the 
earth's  surface  ? 

What  are  the  advantages  of  such  changes  to 
a  country  ? 

How  are  waterfalls  formed  ? 

Can  you  show  the  wasting  effect  of  the  water 
at  the  Falls  of  Niagara  ? 


QUESTIONS    FOR    INVESTIGATION.  157 

How  fast  are  these  Falls  thought  to  recede  ? 

Then  how  long  has  it  taken  for  them  to  recede 
from  Queenstown  to  their  present  place,  a  dis- 
tance of  seven  miles  ? 

How  are  lakes  formed  ? 

What  is  the  cause  of  whirlpools  ? 

Give  an  instance  of  one.  ^/JC^eL^/fco^w  - 

What  peculiar  danger  do  they  bring  to  mari- 
ners ? 

Wrhat  are  inland  seas  ? 

How  do  they  differ  from  lakes  ? 

Describe  the  fiords  of  Norway. 

How  is  the  surface  of  the  earth  heated  ? 

Is  the  earth  nearer  the  sun  in  summer  or  in 
winter  ? 

Upon  what  does  the  amount  of  heat  depend  ? 

What  do  you  mean  by  perpendicular  rays  ? 
by  slant  rays  ? 

Do  perpendicular  or  slant  rays  give  the  more 
heat  ? 

Over  what  zone  does  the  sun's  course  through 
the  year  lie  ! 

Why  are  the  tropics  so  called  ? 

Does  the  sun  move  round  the  earth,  or  the 
earth  round  the  sun  ? 

If  the  axis  of  the  earth  were  not  inclined, 
where  would  the  sun's  rays  fall  perpendicularly  ? 


158  QUESTIONS    FOR    INVESTIGATION. 

How  often  in  the  year  does  the  sun  shine 
vertically  on  the  equator  ? 

Why  are  these  occasions  called  equinoxes  ? 

When  does  the  sun  shine  vertically  on  the 
Tropic  of  Cancer  ?  of  Capricorn  ? 

What  are  these  occasions  termed  ? 

When  the  sun  shines  vertically  on  the  Tropic 
of  Cancer,  how  many  degrees  beyond  the  North 
Pole  can  any  of  the  slant  rays  fall  ? 

How  many  beyond  the  South  Pole,  when  he 
is  at  the  Tropic  of  Capricorn  ? 

Then  what  do  the  Arctic  and  Antarctic  circles 
show? 

How  long  is  the  day  at  the  North  Pole  ? 
Why? 

The  night  ?     Why  ? 

How  many  days  and  nights  in  the  year  at  the 
South  Pole  ?     Why  ? 

If  the  sun  were  shining  vertically  now  on  the 
Tropic  of  Cancer,  which  would  be  the  longer 
here,  the  day  or  night  ? 

If  upon  the  Tropic  of  Capricorn  ? 

If  upon  the  Equator  ? 

What  is  the  shortest  day  of  the  year  to  per- 
sons in  the  Northern  Hemisphere  ?  the  longest  ? 

(The  questions  given  immediately  above  must 
be  resolved  with  the  assistance  of  a  globe.) 


QUESTIONS    FOR    INVESTIGATION.  159 

When  it  is  noon  at  London,  what  will  be  the 
time  at  Boston  ? 

At  six  o'clock,  A.  M.  at  Boston,  what  will  be 
the  time  at  St.  Louis  ?  &t  St.  Petersburg  ? 

When  it  is  three  o'clock,  P.  M.  at  London, 
what  will  be  the  time  at  Bordeaux  ? 

What  is  the  latitude  of  Cape  Horn  ?    }"!"  2. 

What  is  the  Aurora  Borealis  ?  Ij^UA*  > 

How  is  it  thought  to  be  produced?      **tft*»t>i+& 

Is  a  garden  bean  a  cryptogamous  or  a  phseno- 
gamous  plant?    J^Lai************ 

Is  it  mono-cotyledonous  or  di-cotyledonous  ?  M-  t*ty* 

Is  it  endogenous  or  exogenous  ?  d  ^y*£e^«c<j . 

What  is  the  effect  of  light  on  the  colors  of 
blossoms  ?     <# .  ■ .  :+i*^  • 

Describe  the  banian  tree,  and  quote  Milton's 
description  of  it  (P.  L.  ix,  1100). 

Give  so  far  as  you  can  the  flora  of  the  state  in 
which  you  live. 

Give  its  fauna. 


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